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524 Cards in this Set
- Front
- Back
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What is antidiuretic hormone (ADH) also known as?
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Vasopressin
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Where is ADH formed?
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Hypothalamus
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Where is ADH stored?
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Posterior pituitary gland
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What does ADH control?
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Water reabsorption from the kidney.
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When would ADH be secreted?
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In response to low blood volume.
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If the plasma osmolality is ↑ or there is ↓ circulating blood volume, how does the body try to regulate?
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↑ thirst(water intake ↑)
OR ↑ ADH release(↓ H2O excretion) |
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What type of feedback system controls ADH?
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Negative feedback loop
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If the plasma osmolality is ↑ or there is ↓ circulating blood volume -after regulation by the body - how is the urine affected?
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More concentrated.
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If the plasma osmolality is ↓ or there is ↑ circulating blood volume, how does the body try to regulate?
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↓ thirst(water intake ↓)
OR ↓ ADH release(↑ H2O excretion) |
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If the plasma osmolality is ↓ or there is ↑ circulating blood volume-after regulation by the body - how is the urine affected?
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More dilute
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What are two major conditions in which normal ADH secretion is altered?
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1. Diabetes Insipidus
2. Syndrome of Inappropriate ADH secretion |
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What are the two mechanism by which Diabetes Insipidus can occur?
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1. Neurogenic- Amount of ADH is too low
2. Nephrogenic- Kidneys response to normal ADH is NOT normal |
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How is ADH abnormal with SIADH?
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ADH production is too high
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Which is a more common cause of Diabetes Insipidus, neurogenic or nephrogenic?
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Neurogenic(central)
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What are some causes of neurogenic Diabetes Insipidus?
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Brain trauma or tumor, Inflammation of the brain, or surgical ablation (expl:pituitary)
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What are some causes of nephrogenic Diabetes Insipidus?
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Pyelonephritis, renal amyloidosis, myeloma, Sickle cell dz, drug induced, Sjogren's syndrome
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What are two drugs that can cause nephrogenic diabetes insipidus?
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Amphotericin B and Lithium
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What are 6 signs of diabetes insipidus?
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Polydipsia (2-20 L/day)
Polyuria Urine specific gravity < 1.006 Increased serum osmolality Decreased urine osmolality Increased serum sodium |
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What is the 'water deprivation ADH test' differentiating btwn?
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Neurogenic and nephrogenic DI
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How is the 'water deprivation ADH test' administered?
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Water intake is restricted and osmolality is checked, then vasopressin is administered to observe result.
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How would urine osmolality change during the 'water deprivation ADH test' in a pt with neurogenic DI?
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No rise in urine osmolality with water restriction (Not producing ADH to stimulate that effect) and after administration of vasopressin the urine osmolality would rise.
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How would urine osmolality change during the 'water deprivation ADH test' in a pt with nephrogenic DI?
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No rise in urine osmolality after water restriction or after administration of vasopressin.
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What is the most frequent cause of SIADH?
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An exogenous tumor - CA of lung or thymus.
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What does the 'water load' or ADH suppression test differentiate btwn?
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SIADH and other possible causes of hyponatremia or edematous states (like CHF).
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How is the 'water load' test performed?
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Oral water load given over 15-20 min and then urine is collected hourly for the next 5 hours while the pt is recumbent.
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How will pts with SIADH react to the 'water load' test?
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They will excrete little or none of the water load and thier urine osmolality will remain high.
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How would a pt with another form (besides SIADH) react to the 'water load' test?
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They will excrete water and maintain a high urine osmolality.
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How would the following conditions affect ADH levels?
SIADH Nephrogenic DI Severe physical stress Postop days 1-3 Hypovolemia Dehydration |
Increased
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How would the following conditions affect ADH levels?
Neurogenic DI Surgical ablation of the pituitary gland Hypervolemia Decreased serum osmolality |
Decreased
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For what is a CHF patient at more risk for 1-3 days after a surgical procedure?
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Heart failure due to increased ADH levels thereby causing them to retain more water as a result of post op stress.
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Where is aldosterone released from?
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The glomerulosa(adrenal cortex).
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What is aldosterone?
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A mineralocorticoid that influences the renal tubules to increase reabsorption of Na+ in exchange for K+ excretion.
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What are 4 things that might turn aldosterone on?
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1. High K+ levels
2. Hyponatremia 3. Hypovolemia 4. Renin-angiotensin system |
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How does the renin angiotensin system work?
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in notes
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What are 3 things that can turn aldosterone off?
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1. Hypernatremia
2. Hypokalemia 3. Spironolactone (aldosterone antagonist causing K+ conservation) |
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What are some negative effects of aldosterone?
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1. Hypokalemia (in effort to save Na+ you lose K+)
2. Alkalosis (in effort to save Na+ you lose H+) 3. HTN |
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What is the most common cause of HTN?
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Primary or essential (idiopathic)
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How does renin feedback system worK?
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great chart in notes, too much to type :)!
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What does the plasma renin assay (PRA) measure?
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The rate of generation of angiotensin ( that is produced from the renin you secreted).
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What does the PRA test help you to differentiate btwn?
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Essential vs. renal/renovascular HTN (primary and secondary)
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How are aldosterone and renin affected in primary hyperaldosteronism?
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There is an increase in aldosterone (due to an aldosterone secreting tumor) so therefore renin is reduced because it is not necessary.q
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What is a condition that is caused by primary aldosteronism?
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Conn's syndrome (usually in kids) - aldosterone secreting adrenal tumor.
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How are aldosterone and renin affected in secondary hyperaldosteronism?
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You have a normal functioning system that is responding with increased levels of renin and thereby increasing aldosterone.
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What are three important steps to take before getting a PRA?
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1. Stop metformin or glucophage
2. check PT/INR - don't want a bleeder 3. Ask about shellfish/iodine allergy |
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What type of hyperaldosteronism can renal artery stenosis cause?
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Secondary
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What is renin stimulation testing and what are results you are observing for?
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This test separates primary from secondary hyperaldosteronism. The pt is to lie supine for the night then when asked to stand in the morning (change of position) the primary condition would result in no change of renin and secondary would show an increase in renin.
Primary - |
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If you wanted to perform a non-invasive test after hearing a renal bruit (not a PRA) what would you do?
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U/S with doppler
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What is osmolality?
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The concentration of dissolved particles in blood, urine, or other fluids per kg H20.
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How do the normal ranges for urine and serum osmolality differ?
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Urine osmo range: broad
50-1200 Serum osmo range: tight 285-295 |
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What is plasma(serum) osmolality useful for?
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When trying to ID the cause of hyponatremia.
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What is urine osmolality an important test for?
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To determine the renal concentrating ability of the kidney.
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What do stool/fecal osmolality results assist in the diagnosis of?
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The cause of diarrhea.
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In general, what are osmolality values useful for?
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1. Monitor fluid/electrolyte balance
2. Susptected ADH imbalance(DI or SIADH) 3. Eval for: Seizures, ascites, hydration status, acid/base imbalance,coma pts |
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When ordering a chem 7 do osmolality values come automatically?
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No, they must be asked for separately.
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What level of osmolality would you expect with ↑ Serum Free H20 or ↓ Serum particles?
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LOW Serum Osmolality
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What level of osmolality would you expect with ↓ Serum Free H2O or ↑ Serum particles?
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HIGH Serum Osmolality
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How would you expect serum osmolality to be affected with: hypernatremia?
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Increased
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How would you expect serum osmolality to be affected with: dehydration?
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Increased
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How would you expect serum osmolality to be affected with:hyperglycemia?
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Increased
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How would you expect serum osmolality to be affected with: Mannitol therapy?
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Increased
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How would you expect serum osmolality to be affected with:Azotemia/uremia?
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Increased
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How would you expect serum osmolality to be affected with:Ingestion of toxic agent?
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Increased
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How would you expect serum osmolality to be affected with:DI?
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Increased
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How would you expect serum osmolality to be affected with:Hyperosmolar nonketotic hyperglycemia?
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Increased
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How would you expect serum osmolality to be affected with:hypercalcemia?
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Increased
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How would you expect serum osmolality to be affected with:hypercalcemia?
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Increased
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How would you expect serum osmolality to be affected with:Renal tubular necrosis?
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Increased (like a strainer, lose H20)
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How would you expect serum osmolality to be affected with:Severe pyeolonephritis?
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Increased(like a strainer, lose H20)
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How would you expect serum osmolality to be affected with:Ketosis?
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Increased
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How would you expect serum osmolality to be affected with:Shock?
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Increased
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How would you expect serum osmolality to be affected with:hyponatremia?
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Decreased
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How would you expect serum osmolality to be affected with:Overhydration?
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Decreased
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How would you expect serum osmolality to be affected with:SIADH?
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Decreased
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How would you expect serum osmolality to be affected with:Paraneoplastic syndromes associated with Lung CA?
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Decreased
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How would you expect urine osmolality to be affected with:SIADH?
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Increased
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How would you expect urine osmolality to be affected with:Acidosis?
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Increased
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How would you expect urine osmolality to be affected with:Shock?
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Increased
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How would you expect urine osmolality to be affected with:Hypernatremia?
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Increased
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How would you expect urine osmolality to be affected with:Hepatic Cirrhosis?
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Increased
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How would you expect urine osmolality to be affected with:CHF?
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Increased
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How would you expect urine osmolality to be affected with:Addision's Dz?
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Increased
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How would you expect urine osmolality to be affected with:DI?
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Decreased
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How would you expect urine osmolality to be affected with:Hypercalcemia?
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Decreased
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How would you expect urine osmolality to be affected with:Excess fluid intake?
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Decreased
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How would you expect urine osmolality to be affected with:Renal tubular necrosis?
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Decreased
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How would you expect urine osmolality to be affected with:Aldosteronism?
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Decreased
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How would you expect urine osmolality to be affected with:Hypokalemia?
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Decreased
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How would you expect urine osmolality to be affected with:Severe pyelonephritis?
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Decreased
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What is the name of a machine that would measure osmolality?
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Osmometer
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What are the important solvents used to calculate osmolality?
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Sodium, glucose, urea
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What is the equation used to calculate osmolality?
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CO = 2(Na + K) + (Glucose/18) + (BUN/2.8)
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Why is osmolar gap an important value?
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Because some solutes you ingest that do not show up- that you need to know about- in the calculated value will affect the measured value.
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What is equation to calculate osmolar gap?
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OG = measured osmo - calculated osmo
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What are three substances that when present - or are suspected as having been ingested- can cause an increase in osmolar gap?
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Ethanol, methanol, ethylene glycol.
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What are normal serum levels of sodium?
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135-145 meq/L
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What is the major determinant of extracellular osmolality?
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serum sodium
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What are 3 hormones responsible for regulation of sodium?
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1. Aldosterone (conserve Na by ↓ renal losses)
2. Natriuretic hormone (↑ renal losses) 3. ADH (controls H2O reabsorption of water at distal tubules of kidneys) |
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When serum Na+ is decreased what is released?
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Aldosterone
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When serum Na+ is increased what is released?
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ADH
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What are the S/S of hyponatremia?
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GI discomfort, N/V, HA, restlessness, swollen hands/feet, lethary, confusion, wheezing, seizures.
VERY NON SPECIFIC |
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Once it has been established that hyponatremia is present, what comes next?
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Determine what the osmolality is: low-hypotonic, normal-isotonic,high-hypertonic.
Then do get a serum blood sugar and lipids. |
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Once you determine a pt's status to be Hypotonic hyponatremia then what do you want to know?
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Determine the volume status: hypervolemic (overhydration)
dehydration (hypovolemic) euhydration (isovolemic) |
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understand hyponatremia chart!
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understand hyponatremia chart!
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What is true hyponatremia?
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Hypotonic hyponatremia.
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What are signs during the PE that help to indicate volume status?
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Orthostatic vitals, skin turgor, mucous membrane appearance, jugular venous distention, findings of edema, wedge pressure, and CVP (if you can).
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What is normal JVD?
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2-6cm
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What might be 3 causes of hypernatremia?
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1. Overhydration (primary hyperaldosteronism,Cushing's syndrome)
2. Dehydration (Fever, burns, wounds) 3. Free water deficit (DI, excessive Na+ intake) |
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What are some S/S of hypernatremia?
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Dry mucous membranes, thirst, agitation, restlessness, hyperreflexia, mania, convulsions
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How is urine Na+ obtained?
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24 hour urine testing
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What type of Na+ level for urine output would hyponatremia due to low Na+ intake result in?
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Low urine Na+ - the kidney is still working here!
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What type of Na+ level for urine output would hyponatremia due to acute renal failure result in?
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Elevated urine Na+ - the kidney is not working effectively- it is like a colander.
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What is FENa?
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Fractional excretion of Na+
The fraction of Na+ excreted relative to total filtered load. |
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When is the FENa test indicated?
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For renal failure assessment (prerenal azotemia, renal-acute tubular necrosis)
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What is the formula for FENa?
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( (Una x Pcr)/(Pna x Ucr))x100
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What would an FENa of <1% indicate?
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Prerenal azotemia - body is holding on to Na and kidney is working-prerenal.
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What would a FENa of >2% indicate?
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ATN - kidney is not working- renal.
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What is the major intracelluar cation?
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Potassium
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What is normal serum K+?
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3.5-5meq/L
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Once excreted by the kidneys is K+ reabsorbed?- what implications does that have?
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No - so dietary IV K+ must be provided to individuals to maintain levels.
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If there is excessive cell lysis due to a particular cause how is serum K+ affected?
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Increased. can be deadly.
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How should IV K+ be administered and why?
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Slowly because costic to vessles and centrally if you can, but if peripherally you can dilute.
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What are 3 factors K+ concentration depends on?
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1. Aldosterone(↑ renal losses of K+)
2. Na+ resorption (As Na+ is resorbed, K+ is lost) 3. Acid base balance (alkalosis lowers K levels by shifting it into the cell, acidosis increases levels by reversing the process) |
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What are some causes of hyperkalemia?
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Renal failure, Cell death, acidosis
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What are some symptoms of hyperkalemia?
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Irritability, N/V, intestinal colic, diarrhea - NONSPECIFIC
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What are EKG changes seen with hyperkalemia?
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1. Peaked T waves (more K, higher the peak)
2. Widened QRS complex 3. Depressed ST segment |
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What are some signs of hypokalemia?
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those related to ↓ muscle contractility (weakness, paralysis, hyporeflexia, ileus, arryhtmias, increased digoxin sensitivity)
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What are some EKG changes seen with hypokalemia?
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1. Flatted T waves and U waves
(tent fell) |
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What are some conditions that you would want to monitor K+ diligently?
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Uremia (K+ ↑)
Addison’s disease(K+ ↑) Vomiting(K+ ↓) Diarrhea(K+ ↓) Steroid therapy(K+ ↓) Patients receiving diuretics Hypokalemia in patients taking digoxin can cause lethal cardiac arrhythmias! (K+ ↓) |
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Is fasting required to check K+ levels?
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No
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Pts taking what 2 medications should have thier K+ levels monitored?
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Digoxin and diuretics
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How should a pt with emergent hyperkalemia be handled - what would the EKG show to begin with?
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1. EKG: peaked T waves
2. Make sure to ask where the K+ was drawn from (if they are perhaps receiving K+) 3. If really hyperkalemia, give insulin and glucose 4. Get rid of extra K+ with loop diuretic - could also give Kayexalate enema to correct |
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How is a urine K+ obtained?
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Via 24 hour urine.
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What two hormones increase loss of K+?
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Aldosterone and glucocorticoids
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What is a normal value range for chloride levels in the body?
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98-106meq/L
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What ion does chloride usually follow?
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Sodium
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What are signs of hyperchloremia?
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hyperexcitability, shallow breathing, hypotension,tetany
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What are signs of hypochloremia?
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Lethargy, weakness, deep breathing
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What is a normal range for BUN level?
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10-20 mg/dL
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What is urea and what is it directly related to?
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Urea- end product of metabolism (ammonia is converted to urea)
Related to metabolic function of liver and excretory function of kidney. |
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What do elevated BUN levels indicate?
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Azotemia (increased waste products)
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If BUN is abnl what other blood level would you want to check?
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FeNa
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What can cause ↑ BUN levels?
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1. Renal diseases(inadequate excretion)- unless unilateral disease
2. High protein diets or GI bleed 3. Dehydration |
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What can cause ↓ BUN levels?
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1. Overhydration
2. Primary liver dz (ammonia level ↑) |
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What is the BUN/Creatinine ratio used to measure?
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Kidney and liver function - helps to determine if decreased kidney function is the result of dehydration or kidney disease.
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What is the normal range for BUN/Creatinine ratio?
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6-25 (15 optimal)
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How does dehydration affect the BUN/Creatinine ratio?
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The BUN rises out of proportion to creatinine creating a ratio o f >20:1
(Prerenal cause) |
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How would kidney disease obstruction of urine flow affect the BUN/Creatinine ratio?
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BUN and creatinine levels rise equally resulting in a normal ratio (Renal cause)
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What would be some prerenal causes for increased BUN?
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Prerenal-hypovolemia:
Shock, burns Dehydration CHF, Myocardial infarction GI bleeding Excessive feeding Starvation, sepsis |
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What would be some renal causes for increased BUN?
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renal disease, renal failure, nephrotoxic drugs(Amphotericin B and AGs).
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What would be some postrenal causes for increased BUN?
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Uretal obstruction
Bladder obstruction - tumor or BPH. |
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What would be some causes for decreased BUN?
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Liver failure
Overhydration (Fluid overload or SIADH) Malnutrition/Malabsorption Pregnancy Nephrotic Syndrome |
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What is a normal serum creatinine in adults?
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~1
Females: 0.5 - 1.1 mg/dL Males 0.6 - 1.2 mg/dL |
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What is serum creatinine and what does its daily production depend upon?
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Catabolic product of creatine phosphate used in skeletal muscle contraction.
-Depends on muscle mass- fluctuates little |
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Where is creatinine excreted and what organ's function is it proportional to?
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Kidneys - kidney only (not liver)
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What type of disorder might cause an increase in serum creatinine?
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Renal disorders: Glomerulonephritis
Pyelonephritis Acute tubular necrosis Urinary obstruction Reduced renal blood flow Diabetic nephropathy Nephritis Rhabdomyolysis |
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Is Creatinine affected by liver function?
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No - unlike BUN
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If the serum creatinine level doubled what might that suggest about the GFR?
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50% reduction
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What are 4 classes of drugs that might increase serum creatinine?
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1. AGs (Gentamycin)
2. Cimetidine 3. Heavy metal chemotherapeutic agens (Cisplatin) 4. Nephrotoxic drugs(Cephalosporins) |
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What might cause a decrease in serum creatinine?
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1. Debiliation
2. Decreased muscle mass (MD) 3. Myasthenia gravis |
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What is creatinine clearance?
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Measure of glomerular filtration obtained by performing 24 urine and serum creatinine level.
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What does the creatinine clearance depend upon?
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1. Amount of blood to be filtered.
2. Ability of glomeruli to perform its job |
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What is the best test to perform in order to assess GFR and how the glomerulus is doing?
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Creatinine clearance
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What conditions would produce a decrease in blood filtered by the kidneys?
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1. RA stenosis
2. Dehydration 3. Shock |
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What conditions would prevent the glomeruli from filtering properly?
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1. Glomerulonephritis
2. Acute tubular necrosis 3. Bilat renal obstruction (only after a long time though) |
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Can only one normally functioning kidney keep creatine clearance within normal range?
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yes - by increasing GFR enough.
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What are some nonrenal factors that can affect creatinine clearance?
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1. ↓ GFR seen with age
2. Falsely ↓ value with incomplete or mistimed collections 3. Variation of muscle mass -↓ muscle mass = ↓ CC 4. Large meals = ↑ CC (esp. meat) |
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In what pts is ↓ creatinine clearance seen?
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Impaired kidney function
Conditions with ↓ GFR: CHF,cirrhosis with ascites,shock,dehydration |
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What role does the kidney play in homeostasis regulation?
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1. regulation of H20 content
2. Controls electrolyte balance of blood ions 3. Removes waste products 4. performs some endocrine functions(Renin,Erythropoietin,VitD) |
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What are the 3 distinct processes carried out during urine formation?
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1. Plasma filtration (filters small substances into Bowmans)2. Reabsorption (some filtered stuff enters back into the blood) - H20,Na,K,Cl,HCO3,Gl
3. Secretion(substances are released from renal tubules) |
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Why is urinalysis popular?
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Cheap,quick,noninvasive
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How should a urine specimen be collected?
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In a clean dry container, midstream,clean catch - tested within 2 hours or refrigerated
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FYI: what is the best type of urine sample to obtain?
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from a catheter
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What are 10 types of urine specimen that can be collected?
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Random
First morning Fasting 2 hour post-prandial Glucose tolerance test Chain of custody 24 hour timed Catheterized Suprapubic Midstream clean-catch Pediatric bags |
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What are 3 components of the urinalysis and how are they obtained?
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1. Physical(Look at it)
Color, transparency,Odor, volume, Specific gravity 2. Chemical(Dipstick) Protein, glucose, ketone, bilirubin, pH, blood, nitrite, Leukocytes, urobilinogen 3. Microscopic(Scope) Formed elements/ WBC, RBC, Epithelial cells, casts, crystal, microorganisms |
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When looking at urine what is a normal color to see?
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Pale yellow to amber
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What are 3 things that change urine color that are not associated with pathology?
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Food dyes, medications, vitamins
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How would vitamin B change the color of your urine?
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yellow
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How would Flagyl change the color of your urine?
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Brown
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How would beets change the color of your urine?
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red
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If your urine is yellow-brown what abnormality might you attribute that to?
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Bilirubin
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|
|
If your urine is orange-yellow what abnormality might you attribute that to?
|
Urobilin
|
|
|
If your urine is red-brown what abnormality might you attribute that to?
|
Myoglobin (tea colored)
|
|
|
If your urine is green what abnormality might you attribute that to?
|
Biliverdin
|
|
|
If your urine is red what abnormality might you attribute that to?
|
RBC or hemoglobin
|
|
|
If your urine is brown-black what abnormality might you attribute that to?
|
Melanin
|
|
|
What are 5 urine transparency descriptors?
|
clear,hazy,slightly cloudy,cloudy,turbid - normal is clear
|
|
|
What could cause the urine to be cloudy?
|
Cells,bacteria,casts,mucous,
crystals,sperm,fat,fecal contamination,yeast |
|
|
What can cause a pink precipitate in the urine?
|
Crystallization of phosphates and urates (non pathologic)
|
|
|
What are 2 foods that can cause abnormal associated urine odors?
|
Garlic,asparagus
|
|
|
If your urine smelled like ammonia what could cause that?
|
Splitting of the urea moleculte - UTI
|
|
|
If your urine smelled fruity what could cause that?
|
Ketones - result of fat metabolism
|
|
|
If your urine smelled putrid/foul what could cause that?
|
Bacteria or WBC - leukocytes in UTI
|
|
|
If your urine smelled mousey what could cause that?
|
PKU - metabolic disorder (genetic)
|
|
|
Is the urine dipstick analysis qualitative or quantitative?
|
Mostly qualitative
|
|
|
Is the urine sample sensitive to air?
|
Yes- so close the top tightly!
|
|
|
What are specific gravity and osmolality an dcan they be measured on the test strip for urinalysis?
|
SG-ratio of weight of given volume of solution to an equal volume of water at specific temperature
Osmolality- # of solute particles per unit amount of solute SG will suffice- can't measure osmolality on this strip |
|
|
What are the normal values for urine osmolality?
|
1.005 - 1.030
|
|
|
What could cause low urine specific gravity and what is that called?
|
Hyposthenuric hydrated status - DI
|
|
|
What could cause a high urine specific gravity and what is that called?
|
Hypersthenuric-
Neprosis with proteinuria Diabetes with glycosuria SIADH Dehydration Radiographic (Xray)dyes |
|
|
What could cause a fixed urine specific gravity and what is that called?
|
Isosthenuric-
Chronic renal disorder where kidney cannot concentrate the urine - stays about at GFR |
|
|
How does the pH of blood plasma vary in the course of developing urine?
|
The glomerular filtrate of blood plasma is usually acidified by the renal tubules and collecting ducts from a pH of 7.4 to 6 in the urine.
|
|
|
Define the pH level of alkaline urine and what can cause this?
|
>7.0
After meals,bacterial infections,metabolic disorders,chronic renal failure |
|
|
Define the pH level of acidic urine and what can cause this?
|
<6.0
High protein diet,uncontrolled DM, respiratory acidosis |
|
|
Do the kidneys filter protein?
|
Not normally
|
|
|
Do the kidneys filter glucose?
|
Yes, all of it and then it should all be reabsorbed.
|
|
|
What is the hallmark of kidney disease?
|
proteinuria
|
|
|
What is microalbuminuria and what can that be a predictor of?
|
When a small about of albumin is in the urine - this can be a sign of early kidney dz and a predictor for diabetics to go onto renal failure
|
|
|
Once you find proteinuria, then what is important to determine?
|
Whether it is transient or persistent.
|
|
|
What are the 3 types of persistent proteinuria?
|
Glomerular, Tubular,Overflow
|
|
|
What can be some nonpathologic or transient causes of proteinuria?
|
Orthostatic proteinuria(standing all day)
CHF Emotional stress, exercise Fever Seizures Diet |
|
|
If you are found to have proteinuria and the urine contains mostly albumin, what might you suspect?
|
Glomerular proteinuria - Glomerulus is destroyed - like a colander - all is getting through
|
|
|
If you are found to have proteinuria and the urine contains an abundance of low molecular weight proteins, what might you suspect?
|
filtration is okay but reabsorption is poor-->
Either: Tubular Proteinuria - Tubules malfunctioning - you are unable to metabolized or reabsorb. or Overflow Proteinuria - too many small proteins are produced for the kidney to keep up so they overflow into the urine. |
|
|
What does glycosuria generally mean?
|
DM
|
|
|
How might ascorbic acid affect your glucose urine level?
|
False negative
|
|
|
What are ketones?
|
Products of fat metabolism in the body
|
|
|
Are ketones normally found the urine?
|
No
|
|
|
If ketones are found in the urine what might that indicate?
|
Diabetic ketosis or some other type of calorie deprivation (starvation)- can't get glucose so you starte breaking down ketones for food
|
|
|
How might Levodopa affect the urine ketone level?
|
Falsely positive
|
|
|
What might a positive urine nitrite dipstick test mean?
|
bacteria may be present in the urine (they turn nitrates to nitrites)
|
|
|
If your urine dipstck is negative for nitrites does thaht mean there is no UTI?
|
No- this is a very specific test - the bacteria might be gram (+) - The gram negatives like EColi are more likely to result in a positive test.
|
|
|
What does a positive urine leukocyte esterase indicate?
|
The presence of WBCs -either whole or lysed = pyuria
|
|
|
What does a negative urine leukocyte esterase test indicate?
|
An infection is unlikely and without additional UTI evidence - you don't need a microscopic exam or urine culture to r/o bacteremia.
|
|
|
When might a false positive leukocyte esterase exist?
|
FN: those with high protein or ascorbic acid levels
FP: specimen with vaginal secretions |
|
|
How should urinalysis testing order proceed?
|
Dipstick + Leukocyte esterase then if both are + then you want to know the bug and get a culture
|
|
|
What 3 blood elements will a dipstick not differentiate btwn?
|
1. Hematuria - presence of intact RBCs
2.Hemoglobinuria- Presence of hemoglobin 3. Myoglobinuria - protein from muscle tissue causing false + |
|
|
What mechanism and clinical circumstances allows for hematuria upon urine dipstick?
|
Mech: RBCs lyse on contact with reagent pad causing some speckling
Clinical: Bleeding into the urinary space- can occur at any level of the tract |
|
|
What mechanism and clinical circumstances allows for hemoglobinuria upon urine dipstick?
|
Mech: Free Hb filtered into the urine as a result of hemoglobinemia (visible red plasma)
Clinical: Intravascular hemolysis of any cause |
|
|
What mechanism and clinical circumstances allows for myoglobinuria upon urine dipstick?
|
Mech:Free Mb filtered into urine as a result of myoglobinemia (not visually detectable in plasma)
Clin: Myocyte injury allowing release of myoglobin that reaches the blood stream and is readily filtered at the glomeruli. |
|
|
Normally, does the urine have detectable levels of bilirubin?
|
Yes - conjugated because unconjugated cannot pass the glomerulus.
|
|
|
How is urine prepared for microscopic evaluation?
|
Centrifuging urine for about 5 minutes - then it is stained with Sternheimer-Malbin to clarify cells - view covered slide at low and high power
|
|
|
How will RBCs appear in concentrated urine?
|
Crenated - abormal notchings due to loss of water
|
|
|
How will RBCs appear in dilute urine?
|
swollen
|
|
|
If the hemoglobin is released from the RBC how would that RBC appear in the urine?
|
ghost like
|
|
|
Two types of WBCs seen (in the urine)?
|
Granular or agranular
|
|
|
What are 3 types of epithelial cells found in the urine?
|
Squamous,transitional,renal
|
|
|
What are clue cells?
|
Squamous epithelial cells with a small bacterial rods.
|
|
|
How many RBCs per HPF are unacceptable?
|
>2
|
|
|
If a pt presents with asymptomatic hematuria should you worry?
|
Yes, a small percentage have either urological dz or CA.
|
|
|
How would glomerular hematuria show up upon microscopic examination?
|
+ Proteinuria
+ Erythrocyte casts + Dysmorphic RBCs |
|
|
How would Renal (non-glomerular) hematuria show up upon microscopic examination?
|
+ Proteinuria
(-) Erythrocyte casts (-) Dysmorphic RBCs (because they aren't shredded in glomerulus so maybe problem is farther along -tubulointerstitial, renovascular, or from a metabolic disorder. |
|
|
How would urologic hematuria show up upon microscopic examination - what could that result from?
|
(-) Proteinuria
(-) Erythrocyte casts (-) Dysmorphic RBCs Tumors, infections, calculi |
|
|
Where are urinary casts formed from?
|
The lumen of the nephron tubules (Tamm-Horsfall protein)
|
|
|
What are some factors affecting the formation of urinary casts and what types are there?
|
Urinary stasis,Increased acidity, and abnormal protein
Hyaline,RBC,WBC,epithelial, granular,waxy,broad |
|
|
What are factors that favor protein (Hyaline) cast formation?
|
1. Low flow rate
2.High salt concentration 3. Low pH could be seen in healthy pts that are on a high protein diet or exercise a lot |
|
|
What might RBC casts be indicative of?
|
Glomeruloneprhitis (leakage of RBCs from glomeruli) or severe tubular damage
|
|
|
What is the presence of WBC casts indicative of?
|
***Acute pyelonephritis
Also with glomerulonephritis Indicates inflammation of kidney because these can only form in the kidney - maybe a UTI that moved to the kidney |
|
|
What types of microorganisms can be seen under microscopic examination of the urine?
|
1. Bacteria(Cocci or bacilli)
2. Yeast (buds or mycelium) 3. Spermatzoa 4. Parasites (trichomonas,schistosoma) |
|
|
If you see gram (-) rods on microscopic urinalysis what bug is probably there?
|
Ecoli
|
|
|
If you found trichomonas in the urine would you treat the pt's partner as well?
|
Yes
|
|
|
What are some normal crystals found in the urine?
|
Acid urine (Amorphous urate,Uric acid,Calcium oxalate)
Alkaline urine (Amorphous phosphates,Triple phosphate,Ammonium biurate,Calcium phosphate) |
|
|
What are some very uncommon crystals found in the urine?
|
Cystine crystals - urine of neonates with congenital cystinturia or severe liver dz
Tyrosine crystals - congenital tyrosinosis or marked liver impairment Leucine crystals in pts with severe liver dz or with maple syrup urine dz (cannot break down AAs) |
|
|
What are negative and positive findings on a urine culture?
|
(-) <10,000 bacteria/mL urine
(+) >100,000 bacteria/mL urine |
|
|
When would a urine culture be obtained?
|
If you had a high index of suspicion of a UTI and need to know the bug in order to treat the pt
|
|
|
You want to perform the urine culture prior to what?
|
Taking any antibiotics
|
|
|
If your urine culture is positive what would you want to include?
|
Sensitivity testing - this will help you pick out your antibiotic - you can pick the cheapest one that will kill the bug
|
|
|
What is the Antistreptolysin O titer used for?
|
Primarily to determine that a previous streptococcal dz has caused a post-streptococcal infection.
Glomerulonephritis (GABHS) Rheumatic Fever Bacterial endocarditis(GABHS) Scarlet fever |
|
|
How does the Antistreptolysin O titer work?
|
The Streptococcus organism produces an enzyme, streptolysin O -
Streptolysin O is able to kill RBCs.Normal body response to this is production of anti-streptolysin O (a neutralizing antibody) this antibody prevents the lysis of RBC.Detection of ASO appears 1wk to 1 month after the onset of a strep infection. |
|
|
Is ASO specific for certain types of post-streptococcal dz's?
|
No
|
|
|
Do you draw multiple ASO titers?
|
Yes, you want to follow the trend. For example, a rising ASO followed by a slow fall in the titers indicates a previous strep infection.
|
|
|
When is the highest incidence of positive results for ASO titer?
|
During the 3rd week after the onset of acute symptoms of post-strep dz.
|
|
|
There is a new ASO titer that is combined with what that will will detect the specific antigen produced by GABHS?
|
Anti-DNase B - if both are positive then 95% chance of previous strep infection
|
|
|
For acute glomerulonephritis due to post-streptococcal infection, what would you expect the findings of dipstick and microscopic urinalysis to be?
|
Hematuria
Moderate proteinuria RBC,RBC casts(specific for glomerulonephritis) (+) ASO and AntiDNase |
|
|
Strawberry tongue with abnormal ASO?
|
Scarlet fever -GABHS
|
|
|
What is PSA?
|
Prostate specific antigen - found in all males - produced in the cytoplasm of benign or malignant prostate cells
|
|
|
When might a slight elevation of PSA be seen?
|
In pts with benign prostatic hypertrophy, prostatitis,or early CA.
|
|
|
What does BPH present with?
|
Obstructive or irritative voiding symptoms - maybe enlarged prostate upon DRE.
|
|
|
What does prostatitis present with?
|
Fever, irritative voiding sx, perineal or suprapubic pain, exquisite tenderness on DRE, + urine culture
|
|
|
What does prostate CA present with?
|
Prostatic induration on DRE or with GREATLY elevated PSA, usually asymptomatic - rarely systemic symptoms(like wt loss or bone pain)
|
|
|
Following prostate CA and a TURP how are PSA levels affected?
|
They should return to normal.
|
|
|
Can PSA be used as a screening tool?
|
YES!
|
|
|
To screen for prostate CA, at what age should DREs begin?
|
45
|
|
|
For what pts is the DRE and PSA recommended for?
|
1. All men beginning at age 50
2. African-American men beginning at age 40 3. Men with a family history of prostate cancer, beginning at age 40 4. Men who develop persistent urinary symptoms |
|
|
How do PSA values change with age?
|
they increase
|
|
|
What are some factors that can interfere with PSA?
|
1. Rectal examinations
2. Prostatic biopsy or TURP (transurethral resection of the prostate) 3. Ejaculation within 24 hours of the test 4. Recent UTI or prostatitis |
|
|
What was, historically, the test of choice for nephrolithiasis?
|
IVP - now usually US,CT,MRI
|
|
|
Describe IVP procedure.
|
IV infusion of iodinated contrast material (Hypaque or Renograffin) followed by a series of plain films that show the kidneys,ureters, and bladder.
|
|
|
With IVP, why begin with a preliminary plain film before contrast injection?
|
Because a stone and the contrast are radiopaque
|
|
|
How does the body rid itself of the IVP contrast?
|
through the kidney in the glomerular filtrate.
|
|
|
What is the nephrogram phase of the IVP?
|
<1 minute after injection, the radiopaque solution enters the glomeruli and tubules - this is the proper time to evaluate the size and shape of the kidneys.
|
|
|
If the ureters do not have a straight stream of contrast during an IVP is that okay - what does obstruction cause?
|
Yes, they might not be seen continuously filling.
Obstruction- delayed filling of structure and decrease contrast material |
|
|
What are some contraindications to IVP?
|
1. Shellfish/iodinated dye allergies
2. Severe dehydration -dont want to induce renal failure 3. Renal insufficieny (BUN change) 4. Multiple myeloma 5. Pregnancy-unless benefits outweigh risks-try U/S |
|
|
What are potential complications of IVP?
|
1. Allergy - can pretreat with corticosteroids or antihistamine
2. Infiltration 3. Renal failure (check BUN/Creatinine) 4. Hypoglycemia or acidosis in pts taking glucophage(metformin) |
|
|
What are some factors that can interfere with IVP?
|
Fecal material, gas, barium in bowel can all obscure renal system - or abnl renal function
|
|
|
Post IVP, what is important to do?
|
Maintain oral or IV hydration and assess urine output
|
|
|
What is the test to rule out 'Post renal causes of renal failure'?
|
U/S
|
|
|
Specifically what is U/S the technique of choice for?
|
1. Hydronephrosis (post renal cause)
2. Anechoic benign cysts vs echogenic renal tumors 3. Renal size (small or large dilated) |
|
|
How does a hydronephrotic kidney appear on U/S vs a normal kidney?
|
Normal: kidney with echogenic center without a dilated collecting system.
Hydronephrotic: Fluid filled calyces producing an echofree center - bet on post renal cause (BUN/Cr ratio ~normal) |
|
|
What is the most important distinction U/S can make for renal tumors?
|
Cyst (benign) vs. Solid Mass
|
|
|
Can a malignant renal mass be differentiated from a benign mass by imaging?
|
No
|
|
|
Are solid renal masses fine needle biopsied to determine if they are malignant?
|
No- they are removed - you dont want to seed any CA cells.
|
|
|
What could CT provide with a renal tumor that US cannot?
|
If there are any associated lymph nodes.
|
|
|
What is a limiting factor for CT?
|
The view is only in the axial plane.
|
|
|
What is the procedure of choice for obstructing urethral stone? Advantage?
|
noncontrasted helical CT - c/o contrast the procedure is so fast - benefit: if the etiology is not a stone the CT will help to ID other causes of flank pain: Leaking AAA, diverticulitis,Appendicitis
|
|
|
When might an IV contrasted helical CT be ordered?
|
After US indicates a solid mass or there is a mass that appears cystic but has thick walls (complicated).
|
|
|
Why might you add PO contrast to and IV contrasted helical CT?
|
If you wanted to view other structures as well.
|
|
|
In what way can a CT characterize a tumor?
|
1. Extent
2. Details the vascularity 3. Presence of necrosis 4. Local invasion of tissues (renal vein or IVC) |
|
|
What details do MRI scans provide that other forms of imaging might not, what restrictions to this modality are there?
|
More detail about a soft tissue tumor. - the pt must be stable and have NO iron in their body (like from an implant)
|
|
|
Does IVP require bowel prep?
|
No
|
|
|
What is cystography the best test for?
|
Primary pathologic bladder conditions.
|
|
|
What imaging modalities are used to perfom cystography?
|
Xray and contrast dye
|
|
|
What types of bladder pathology can be identified by cystography?
|
Primary bladder tumors
Pelvic tumors (i.e.. rectal, cervical) Hematoma-due to pelvic trauma Traumatic rupture, perforation or fistulas Vesicoureteral reflux |
|
|
How is the dye administered into the bladder during cystography?
|
retrograde
|
|
|
What is important to always suspect with pelvic injury?
|
Bladder tear
|
|
|
How is the cystography procedure performed?
|
1. Urinary catheter placed and ~300mL of radiopaque dye is injected into the bladder (less for kids)
2. The catheter is clamped and imaging is performed with fluroscopy or xray films (CT is being used too)3. |
|
|
What is a voiding cystourethrography?
|
After imaging is done during the cystography, if the pt can void, the catheter is removed and the pt is asked to urinate so films of the urethra can be taken.
|
|
|
What are 2 potential complications of cystography?
|
1. UTIs
2. Allergic rxn to the dye |
|
|
What is a contraindication to cystography?
|
Documented urethral or bladder infection
|
|
|
What are important preprocedure cystography steps?
|
1. Clear liquids on the day of the test.
2. Confirm dye allergies 3. Males are to shield testes |
|
|
What is important following the cystography?
|
1. Assess for signs of UTI
2. Encourage fluids |
|
|
If you see blood at the urethral meatus and upon DRE there is no prostate or no displaced/high riding prostate what should you suspect and what test should be ordered, how does it work?
|
Urethral injury - order Retrograde Urethrography
A foley catheter is placed in the urethral meatus- the balloon is inflated a bit- and dye is injected into the urethra - and pictures are taken. You are looking for extravasation of the dye. |
|
|
What might abnormal findings on a retrograde urethrography indicate?
|
Fistulas or false passages
Lacerations Strictures Tumors Congenital abnormalities |
|
|
What does cystoscopy allow visualization of?
|
Direct visualization of bladder and urethra
|
|
|
Is cystoscopy diagnostic or therapeutic?
|
both
|
|
|
What are some diagnostic uses for cystoscopy?
|
Direct inspection and biopsy of prostate, bladder, & urethra
Collection of urine Measurement of bladder capacity & determining ureteral reflux Identify bladder & ureteral calculi Identification of source of hematuria |
|
|
What are some therapeutic uses for cystoscopy?
|
Resection of small, superficial bladder tumors
Removal of foreign bodies and stones Dilation of urethra & ureters Placement of catheters Coagulation of bleeding Implantation of radium seeds into a tumor Resection of hypertrophied or malignant prostate gland* -(TURP) Placement of ureteral stents |
|
|
What does a cystoscope consist of?
|
An obturator and a telescope
|
|
|
What are some potential complications of cystoscopy?
|
Perforation of the bladder
Sepsis by seeding the bloodstream with bacteria from infected urine Hematuria Urinary retention |
|
|
What positioning is cystoscopy performed in and is informed consent required?
|
Lithotomy- feet in stirrups
Yes |
|
|
What type of changes should you be aware of post cystoscopy?
|
1. Orthostatic changes
2. Urinary retention 3. Urine color change (pink common but bright red or clots are not normal) 4. Back pain, spasms, urinary frequency, burning on urination 5. BP drop and HR increase 6. Sepsis signs *Do encourage fluids |
|
|
After cystoscopic surgery, what should be encouraged (esp after TURP)?
|
Cathartics
|
|
|
If post cystoscopic procedure irrigation is ordered then what would the isotonic solution contain?
|
Mannitol,glycine, or sorbitol
|
|
|
What is the most common cause of secondary HTN?
|
Renal artery stenosis (RAS)
|
|
|
With RAS, what might you hear upon physical exam?
|
a bruit
|
|
|
What are 8 clincial features suggesting RAS?
|
Hypertension refractory to multiple meds
Renal impairment with ACE Inhibitor Hypertension + unexplained renal impairment Accelerated or malignant hypertension Unilateral small kidney Epigastric/flank bruit Hypertension + extensive arteriosclerotic dz. Severe hypertension before age 30 or after 50 |
|
|
What are 2 causes of RAS?
|
1. Atherosclerosis (70%) -usually unilateral
2. Fibromuscular dysphagia (30%) may be bilat |
|
|
What type of imaging is ordered first to evaluate RAS?
|
MR or CT angiography - noninvasive
Gold standard though - Renal angiography |
|
|
How does the body normally compensate for RAS( plaque in afferent arteriole)?
|
Plaque in afferent arteriole→ ↓ GFR →
JG cells secrete renin → Ang II forms → vasoconstriction of efferent artery to maintain GFR |
|
|
What is ACE inhibitor scintigraphy?
|
Radiolabelled molecule (DTPA or Mag3 is given) and 2 imaging studies are done. One normal and one with the ACE inhibitor.
Baseline picture - no change in uptake bc the kidney is compensating after ACE inhibitor - the efferent arteriole dilates and uptake of the radiolabelled molecules decreases - whereas this would not occur with a normal kidney |
|
|
What can Doppler U/S show?
|
Velocity elevations and abnormal arterial waveforms which result from hemodynamically significant stenosis
|
|
|
What is CT angiography?
|
Vascular imaging using spiral CT - rapid scanning following bolus infusion of IV contrast
|
|
|
What is MR angiography?
|
Magnetic field and radio waves in short pulses are used to generate images
|
|
|
If a pt is experiencing scrotal pain and you want to R/O testicular torsion, what test would you perform?
|
Doppler U/S of scrotum - normal US won't work because you can't see arterial and venous blood flow
|
|
|
What are the present uses for scrotal U/S?
|
Evaluate scrotal masses
Measure testicular size Evaluate scrotal trauma Evaluate scrotal pain Evaluate occult testicular neoplasm Surveillance of pts. with tumors Follow-up for testicular infections Locate position of undescended testicles Provide guidance for needle biopsy of tumor |
|
|
What projections is the scrotal US performed in?
|
Sagittal, transverse,and oblique projections
|
|
|
Concerning the genitourinary system, what imaging modality would be used for stones or stend position?
|
Plain film
|
|
|
Concerning the genitourinary system, what imaging modality would be used for mass or infection?
|
CT
|
|
|
Concerning the genitourinary system, what imaging modality would be used for obstruction or ARF(post renal)?
|
US
|
|
|
Concerning the genitourinary system, what imaging modality would be used for stone or ureteral reflux?
|
IVP
|
|
|
Concerning the genitourinary system, what imaging modality would be used for RAS or obstruction?
|
nuclear medicine
|
|
|
Look at common applications chart in UG imaging notes at end
|
.
|
|
|
What does the thyroid control?
|
Basic metabolic rate
|
|
|
What is the process of evaluation of thyroid function?
|
1.Tests of thyroid hormones in blood
2. Evaluation of the hypothalamic-pituitary-thyroid axis 3. Measurement of thyroid autoantibodies. 4. Assessment of iodine metabolism 5. Estimation of gland size 6. Thyroid biopsy |
|
|
What subunit gives TSH its distinct biological activity?
|
The beta subunit
|
|
|
Hormones released by the anterior pituitary?
|
FSH/LH,ACTH,GH, PRL
TSH |
|
|
What are 5 major functions of thyroid hormones?
|
Promotes normal growth and development
Regulate HR & myocardial contractility Affect GI motility and renal water clearance Modulate energy expenditure, heat generation, and weight. Parafollicular or C cells produce calcitonin which inhibits inhibits bone resorption |
|
|
What are some S/S of hypothyroidism?
|
Hair thinning,depression,big tongue,croaky voice,dry skin,cold skin, cold intolerance,slowing of mind and body, constipation,myxedema,slow reflexes, high LDL, weak heart beat
|
|
|
What would an example of primary hypothyroidism be?
|
Autoimmune- Hashimotos
|
|
|
What is Plummer's disease (AKA toxic adenoma,toxic multinodular goiter)?
|
Toxic nodular goiter involves an enlarged thyroid gland that contains a small rounded mass or masses called nodules, which produce too much thyroid hormone.
|
|
|
What are S/S of hyperthyroidism?
|
Lid lag, sweating, neurotic anxiety, fine tremor, brisk reflexes, low LDL, diarrhea,wt loss, increased appetite, a-fib
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|
|
What is the test of choice for thyroid disorders?
|
TSH - except for newborns for whom you test total T4(if that is abnormal you then test TSH)
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|
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In primary and secondary hypothyroidism what would you expect for TSH levels?
|
Primary - high
Secondary - low |
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|
During exogenous thyroid replacment therapy, at what level would you like to keep TSH?
|
<2
|
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If you suspect a newborn to have a thyroid disorder how would you expect the T4 and TSH levels to measure?
|
↓ T4 & normal or ↑ TSH
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|
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If you suspect a newborn to have a pituitary disorder how would you expect the T4 and TSH levels to measure?
|
↓ T4 & ↓TSH
|
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Which of the thyroid compounds is usually the culprit in primary hyperthyroidism?
|
T4
|
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If you have a patient that is euthyroid (T3,T4) but you want to check thier compliance, what lab would you order?
|
TSH - which would be elevated if you were not taking your medications for some period of time.
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|
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What factors can interfere with TSH levels?
|
1. Severe illness decreases TSH levels
2. Drugs that ↓ levels= aspirin, dopamine, heparin, steroids, and T3,T4 3. Drugs that ↑ levels= antithyroid meds, lithium, potassium iodide, TSH injections |
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What type of TSH levels would you expect with primary hypothyroidism or Hashimoto's,thyroid agenesis, or congenital cretinism?
|
increased
|
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What TSH levels would you expect with
|
Secondary hypothyroidsim, hyperthyroidism, pituitary hypofunction, pregnancy esp 1st trimester(HcG secretion from placenta)
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What has TSH stimulation testing been replaced with?
|
Sensitive TSH testing (immunoassay)
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What is thyroid binding globulin?
|
The major thyroid hormone carrier in serum.
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Does bound or unbound T3 and T4 provide negative feedback to the pituitary and hypothalamus?
|
Unbound
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What is important concerning elevations in TBG levels?
|
These can cause the misdiagnosis of increase in T4 levels(hyperthyroidism) - so if your T4 is elevated make sure to assess your pt for causes of underlying elevations in TBG.
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What are some conditions that can lead to ↑ TBG levels?
|
1.Pregnancy
2.HRT 3. Oral contraceptives 4. Some cases of porphyria & infectious hepatitis 5. Drugs: Estrogens, methadone, tamoxifen, OCP |
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|
What are some conditions leading to ↓ TBG levels?
|
1. Hypoproteinemia (nephrotic syndrome,GI malabsorption,malnutrition)
2. Drugs(Steroids,Androgens,Danazole, Dilantin,Propanolol) |
|
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Other names for T3 and T4?
|
T3-Thyroxine
T4-Triiodothyronine |
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|
What is the majority of thyroid hormone composed of?
|
T4
|
|
|
What is total T4?
|
99% bound(inactive) + 1% unbound and metabolically active
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|
|
What is the usefulness of monitoring total T4?
|
1. Newborn screening for congenital hypothyroidism (combined with TSH)
2. Evaluation of hyper/hypothyroid states in those not likely to have problems with TBG 3. Monitor replacement & suppression hormone therapy |
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|
What are some factors that can interfere with total T4 levels?
|
1. ↑ levels by iodinated xray contrast,pregnancy,drugs(see TBG for changes)
2. ↓ levels by (same drugs that decrease TBG) |
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|
Where and when are newborns screened for total T4 levels?
|
Heel stick prior to discharge after birth.(2-4 days after birth) - you want to saturate the filter paper with blood
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|
Conditions in which total T4 is ↑?
|
Grave’s disease
Plummer’s disease Toxic thyroid adenoma Acute thyroiditis Factitious hyperthyroidism Struma ovarii Pregnancy Hepatitis Congenital hyperproteinemia |
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|
Conditions in which total T4 is ↓?
|
Cretinism
Surgical ablation Myxedema Pituitary insufficiency Hypothalamic failure Protein depleted states Iodine deficiency Renal failure Cushing’s disease Cirrhosis |
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|
Normal values for free T4?
|
0.8 - 2.8 ng/dL
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|
|
What is free T4 used to determine?
|
Thyroid function - also if ↑ TBG this is used
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|
What are the two ways that free T4 can be measured?
|
1. Serum
2. Calculated Free T4 index |
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|
Equation to determine Free T4 index?
|
= [Total T4 x T3 uptake(%)]/
100 |
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|
What does T3 Uptake estimate?
|
the amount of non occupied(unsaturated) thyroid binding sites on serum protein.
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|
|
Conditions that will ↑ Free T4?
|
Grave’s disease
Plummer’s disease Toxic thyroid adenoma Acute thyroiditis Factitious hyperthyroidism Struma ovarii |
|
|
Conditions that will ↓ Free T4?
|
Cretinism
Surgical ablation Myxedema Pituitary insufficiency Hypothalamic failure Iodine deficiency Renal failure Cushing’s disease Cirrhosis |
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Describe T3 % uptake testing.
|
The free labeled hormone in the serum is measured and reported as a percentage of the total labelled hormone added.
↑ T4 due to ↑ TBG-> radiolabeled T4 given to pt-> T4 binds to TBG -> RT3U low ↑ T4 due to Hyperfxn gland-> radiolabeled T4 given to pt;TBG=normal-> T4 binds to TBG (excess left in serum)-> RT3U high or normal |
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What does Total T3 measure?
|
Bound 70% inactive T3 + unbound 30% active - only useful for dx of pts with thyrotoxicosis due to ↑ in T3 only.
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Are Total T3 levels affected by non-thyroid disease?
|
Yes
|
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|
What are some factors that can interfere with Total T3?
|
1. Radioisotope admin
2. ↑ during pregnancy 3. Drugs that ↑ levels: Estrogen,methadone,OCP 4. Drugs that ↓ levels: Steroids,androgens,dilantin, propanolol |
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|
What conditions can ↑ Total T3?
|
Grave’s disease
Plummer’s disease Toxic thyroid adenoma Acute thyroiditis Factitious hyperthyroidism Struma ovarii Pregnancy Hepatitis Congential hyperproteinemia |
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|
What conditions can ↓ Total T3?
|
Hypothyroidism
Surgical ablation Myxedema Pituitary insufficiency Hypothalamic failure Iodine deficiency Cretinism Hypoproteinemia states Cushing’s disease Cirrhosis, Renal failure |
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Anything that drives up total T4 will drive what up?
|
Total T3
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|
When does antithyroglobulin antibody occur?
|
When thyrglobulin, which normally exists in the blood and thyroid, acts as an immune stimulating antigen - autoantibodies react against the thyroglobulin in the thyroid cells - this leads to thyroid inflammation and destruction.
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|
What is antithyroid peroxidase antibody (Anti-TPO or TPO-Ab)?
|
A microsomal antibody against a specific part of the cell in the thyroid gland.
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|
What two autoimmune thyroid antibody levels are performed together usually?
|
Antithyroglobulin antibody and antithyroid peroxidase antibody (Anti TPO or TPO-Ab)
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|
What pts would probably have Anti TPO?
|
Almost all with Hashimoto's thyroiditis, most with Grave's dz, and some with autoimmune disorders like RA.
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|
Primary cause of hypothyroidism worldwide- 4 other causes?
|
1.Iodine deficiency
2. Autoimmune (Hashimoto's-chronic lymphocytic) 3.Neonatal hypothyroidism due to thyroid dysgenesis 4. Iatrogenic cause (tx or thyroidectomy) 5. Drugs (iodine excess - contrast material, amiodarone) |
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|
What are 3 secondary causes of hypothyroidism?
|
1. Hypopituitarism-tumors
2.Isolated TSH deficiency 3.Hypothalamic dz-tumors |
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|
Pretibial myxedema is see with what condition?
|
Usually a skin change with Graves dz(thickening of the skin)
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|
|
What are some primary causes of hyperthyroidism?
|
1.Graves
2.Toxic multinodular goiter 3.Toxic adenoma(plummer) |
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|
What is a secondary cause of hyperthyroidism?
|
TSH secreting adenoma
|
|
|
What can thyrotoxicosis without hyperthyroidism referred to as?
|
Subacute thyroiditis
|
|
|
How are lab values affected wiht primary hyperthyroidism?
|
TSH ↓
Free T4 ↑ Total T4 ↑ T3 ↑ |
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|
How are lab values affected wiht primary hypothyroidism?
|
TSH ↑
Free T4 ↓ Total T4 ↓ T3 ↓ |
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|
How are lab values affected wiht secondary hypothyroidism?
|
TSH ↓
Free T4 ↓ Total T4 ↓ T3 ↓ |
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|
What are 3 types of radiotracers used for thyroid scanning?
|
Technetium 99m, Iodide 125,Iodide 131
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|
|
For what is Technetium 99m used for during thyroid scanning?
|
This label is attached to iodine and is trapped by the thyroid gland via the Na/I symporter. The radiation has about a 6hr half life and the same uptake pattern as iodide 90-95% of the time. Inexpensive.
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|
For what purpose is Iodide 125 used during thyroid scanning?
|
Primarily for total body CA scans - this is very expensive. Less radiation than I-131. 13 hour half life.
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|
For what purpose is Iodide 131 used during thyroid scanning?
|
Same as other radiotracers but in addition, it is used for treatment for hyperthyroidism and post op thyroid CA. Half life is 8 days.
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|
During a normal thyroid nuclear scan how would you expect uptake to occur?
|
Global uptake, no areas of increased or decreased uptake.
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|
What are 3 clinical indications for thyroid imaging?
|
1. Evaluation of enlarged thyroid
2. To check functional status of a palpable nodule 3. Postoperative F/U of thyroid CA |
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|
Being that one indication for thyroid scanning is an enlarged thyroid, what are 4 possible causes for the enlargment?
|
1. Chronic thyroiditis(Hashimoto's-autoimmune)
2. Hyperfunctional goiter(graves) 3.Toxic multinodular goiter 4.Toxic adenoma |
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|
How would chronic thyroiditis-Hashimoto's- affect the nuclear thyroid scanned image?
|
Non-uniform decreased uptake on scan.
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How would hyperfunctional goiter(graves) affect the nuclear thyroid scanned image?
|
Diffusely enlarged gland with uniform increased trapping of radiotracer.
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How would toxic multinodular goiter affect the nuclear thyroid scanned image?
|
Multiple focal "hot" defects on scan.
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How would toxic adenoma affect the nuclear thyroid scanned image?
|
Single focal "hot" defects on scan
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|
Basically what is Graves dz caused by?
|
Increased stimulation of thyroid by IgG that cross reacts with TSH receptor sites causing over production of thyroid hormone.
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|
What are the two classifications for functional status of a palpable thyroid nodule- what could each indicate?
|
Functioning-warm/hot(Benign adenoma,localized toxic goiter)
Non-functioning-cold(cyst,carcinoma,nonfunctioning adenoma or goiter,lymphoma) |
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|
What type of nodule are thyroid cancers normally?
|
cold nodules
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If you detect a cold nodule following a nuclear thyroid scan, what next?
|
U/S guided FNA
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|
How often are full body scans performed for postoperative thyroid CA pts?
|
Every 1-2 years in pts with nodules >1cm
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|
What is the most common cause of thyroid CA?
|
Papillary-more benign course
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|
Which type of thyroid CA is associated with the worst prognosis?
|
anaplastic
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|
What are the contraindications for thyroid scanning?
|
Allergies to iodine and shellfish.
Pregnancy. |
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|
What is a potential complication of thyroid scanning?
|
Radiation induced oncogenesis - best to used Tech99 or I125 over I131
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|
What are some factors that can interfere with thyroid imaging?
|
1.Iodine containing foods
2.Recent xray contrast agents 3.Drugs:vitamins,OCP,thyroid drugs |
|
|
Is fasting required for a thyroid scan?
|
No
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|
|
How long after oral admin of Tech 99 can scanning begin - with the other radiotracers?
|
2 hours
others- 24 hrs |
|
|
What is RAIU?
|
Radioactive Iodine Uptake - pt is given radiolabeled Iodine and a scanner is passed over thyroid to assess uptake
|
|
|
What are normal values for RAIU?
|
After 6 hours: 5-15%
After 24 hours:8-30% |
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|
If there is an abnormal increase in RAIU - what do you suspect?
|
Hyperthyroidism
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|
|
If there is an abnormal decrease in RAIU - what do you suspect?
|
Hypothyroidism
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|
|
What percentage of thyroid nodules are benign?
|
More than 90%
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|
|
What are some risk factors for thyroid CA in those with a thyroid nodule?
|
History of head and neck irradiation
Age <20 or >70 years Increasing nodule size (>4cm) New or enlarging neck mass Male gender Family history of thyroid cancer Vocal cord paralysis, hoarse voice Nodule that is “fixed” to adjacent structures Suspected lymph node involvement Iodine deficiency (follicular cancer) |
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|
Clinically, what is the best way to find a thyroid nodule?
|
PE
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|
About how large must a thyroid nodule be for possible palpation?
|
>1cm
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|
What is the ability of a thyroid nodule influenced by?
|
1. Location within the thyroid gland
2. Anatomy of the pts neck 3. Practitioner's experience |
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|
What nerve that innervates the thyroid also innervates the voice box?
|
Recurrent laryngeal nerve (Posterolateral)
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|
What type of nodule (solitary or multinodular) is more likely to be CA?
|
Solitary
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|
After detecting a thyroid nodule and ordering a TSH you find the levels to be low - what next?
|
You are betting hyperfunctioning thyroid so do a thyroid scan.
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|
|
Is FNA necessary for a hot nodule, cold?
|
No - they are almost never malignant - you should do a FNA for a cold nodule
|
|
|
After detecting a thyroid nodule and ordering a TSH you find the levels to be normal - what next?
|
FNA
|
|
|
What are potential complications of FNA of a thyroid nodule?
|
Bleeding or airway compromise
|
|
|
What are 4 categorizations of FNA results of the thyroid?
|
1. Nondiagnostic(Can't help)
2. Benign 3. Malignant 4.Suspicious |
|
|
What is thyroid U/S valuble for?
|
1. Distinguish btwn cystic and solid
2. Provide improved sampling when combined with FNA 3. Screening post-tx following medical/surgical therapy 4. Procedure of choice in eval of pregnant pts |
|
|
Is fasting/sedation req'd for thyroid U/S?
|
No
|
|
|
How would a hyperechoic area on an U/S appear?
|
Dark
|
|
|
What would be a valuble addition to thyroid U/S?
|
doppler - so you can look at the vasculature of the nodule)
CA - likely to have blood supply whereas a cyst would not |
|
|
What are some U/S characteristics that suggest a benign thyroid nodule?
|
1. Nice sharp edges around nodule
2. Fluid filled and not live tissue 3. Lots of nodules throughout the thyroid(usually benign multinodular goiter) 4. No blood flowing through it(no blood flowing through) |
|
|
From where is Calcitonin secreted and what effect does it have?
|
C cells of the thyroid gland -
Inhibits bone resorption by regulating # and activity of osteoblasts. Secreted in response to high blood calcium levels and prevents abrupt changes in Ca levels. |
|
|
What are some clinical uses for measuring calcitonin?
|
1. Eval pts with/suspected medullary carcinoma(75% of pts with this have ↑ calcitonin)
2. Monitor response to therapy and predicting recurrences of medullary thyroid CA 3. Screening in those with fm hx of medullary Ca |
|
|
In pts with elevations in Calcitonin and (+) Fm hx for medullary thyroid CA, what tests can be performed?
|
1. Pentagastrin stimulation
2. Calcium infusion test |
|
|
What is the calcium infusion test?
|
In pts with a family hx of medullary CA of the thyroid and ↑ calcitonin levels you might perform this.
IV Ca2+ infusion over 1 minute and the post infusion levels are measured at 5 and 10 minutes. Presence of medullary CA of thyroid causes calcitonin to rise significantly. |
|
|
What are some other conditions where elevated calcitonin levels would be seen (other than medullary CA of the thyroid)?
|
1Cancer of the lung, breast, & pancreas
2Pregnancy 3Drugs: calcium, cholecystokinin, epinephrine, glucagon, pentagastrin, and OCP |
|
|
Is fasting required prior to a calcium infusion test?
|
yes-overnight
|
|
|
What two endogenous steroids can bind to mineralocorticoid receptors?
|
Mineralocorticoids and glucocorticoids
|
|
|
Where are the adrenal glands located?
|
Above each kidney in the perineprhic fat
|
|
|
Where are androgens for females primarily found, males?
|
Zona reticularis of the adrenal glands - males: testes
|
|
|
Can any other endogenous steroids bind to glucocorticoid receptors?
|
No, only cortisol
|
|
|
When corticotropin releasing hormone is released from the hypothalamus and stimulates the release of ACTH what other substance is released from the pituitary?
|
Beta Lipoprotein which is involved in melanocyte stimulation.
|
|
|
What can stimulate release of neuropeptides that can stimulate the hypothalamic-pituitary-adrenal axis?
|
Stress
|
|
|
What are the 2 binding systems for cortisol (glucocorticoid)?
|
Alpha2 globulin(CBG) and albumin.
|
|
|
What type of cortisol is cleared through the kidney?
|
Free (unbound) cortisol-the active form + cortisol metabolites(inactive form)
The protein-bound cortisol is not cleared through the kidney - too big. |
|
|
Which pt would have more cushingoid S/S, the one with overproduction of endogenous cortisol or the one taking exogenous cortisol long term?
|
The pt on exogenous cortisol because there is less afffinity for this type of synthetic cortisol at the glucocorticoid binding sites and therefore more active compound is available.
|
|
|
What state increases cortisol binding globulin (CBG)?
|
High estrogen states
|
|
|
What enzyme can activate or deactivate cortisol and where is it located?
|
11ß-HSD I- expressed in liver converts inactive cortisone to active glucocorticoid (cortisol)
11ß-HSD II- expressed in a number of tissues converts cortisol to inactive metabolite (cortisone) |
|
|
What single lab can establish adrenal disease?
|
None- multiple labs are required.
|
|
|
If you suspect endocrine disease it is important to do what?
|
Consult an endocrinologist
|
|
|
Cushing's syndrome is caused by an increase in what?
|
Cortisol
|
|
|
An increase in cortisol, as seen with cushing's syndrome, has what other physiologic effects?
|
Gluconeogenesis- ↑ glucose
Anti-inflammatory Immune suppression - ↓ lymphocytes & eosinophils Mineralocorticoid affect - Na+ reabs/K+ excretion |
|
|
Why would you give cortisol during an anaphylacic rxn?
|
It has an immediate anti-inflammatory response
|
|
|
When cortisol is increased in the blood what type of bone does it like?
|
Trabecular not compact
|
|
|
What are some S/S seen with Cushing's syndrome?
|
Emotional disturbance,memory deficiency, insomnia
Moon facies Osteoporosis Buffalo hump Cardiac hypertrophy(HTN) Glucose intolerance Gastric ulcer Central obesity-peripheral wasting Abdominal striae Thin wrinkled skin Amenorrhea Muscle weakness Purpura Skin ulcers(poor wound healing) |
|
|
What are the two categorizations of Cushing's syndrome?
|
Dependent and Independent
|
|
|
What are some examples of an ACTH dependent conditions?
|
Cushing's dz - pituitary adenoma secreting excess ACTH
Ectopic ACTH syndrome-oat cell lung CA secreting excess ACTH Exogenous ACTH-Oral ACTH excess |
|
|
What are some examples of ACTH independent conditions?
|
Adrenal adenoma or CA- secretion of cortisol
Exogenous Cortisol- oral cortisol excess |
|
|
What subcategory of Cushing's syndrome (dependent or independent) should have no response to the Dexamethasone suppression test?
|
ACTH independent
|
|
|
What is the most common cause of Addison's disease in the US? Worldwide?
|
Autoimmune
TB |
|
|
What is primary Addison's disease?
|
Primary- usually a problem with the entire adrenal gland (autoimmune,TB,post steroid therapy)
(Decreased cortisol (also sometimes Aldosterone decrease) + ↓ glucose, ↑ K, ↑ lymphocytes & Eosinophils) - There will be an increase in ACTH - |
|
|
What is secondary Addison's disease?
|
Decrease in cortisol due to hypopituitarism - there would be a decrease in ACTH and no decrease in aldosterone
|
|
|
Differentiate the ACTH levels for different causes of Cushing's syndrome:
Ectopic ACTH-producing tumor Ectopic ACTH-Cushing dz Adrenal carcinoma/adenoma |
1. Ectopic ACTH-producing tumor (usually lung, pancreas, thymus, or ovary)
High ACTH levels >200 pg/ml 2. Ectopic ACTH-Cushing dz Elevated ACTH levels 30-150pg/ml 3. Cushing Syndrome caused by adrenal adenoma or CA Low ACTH levels |
|
|
What are important procedural notes for serum ACTH testing?
|
1. NPO after MN
2. Eval for stress factors that would invalidate the test 3. Eval for sleep pattern abnormalities(night workers) 4. On Test day: Collect 20ml of heparinized venous blood and chill tube fast! |
|
|
What conditions can ACTH testing give insight into?
|
Cushings syndrome or Addison's disease
|
|
|
What type of variation is seen with ACTH and what other substance does it correspond to?
|
Diurnal variation that corresponds to that of cortisol
|
|
|
What are some factors that can interfere with ACTH testing?
|
1. Stress (trauma,pyrogens,hypoglycemia)
2. Pregnancy 3. Recent Radioisotope scanning 4. Drugs: increase-estrogens,ethanol decrease-corticosteroids 5. Susceptible to plasma proteases after specimen is drawn and tends to stick to glassware |
|
|
What are some drawbacks of ACTH?
|
1. Expensive
2. Not very sensitive 3. Plasma must be drawn into iced purple top tube and frozen immediately |
|
|
What are 5 conditions that could reveal an increase in serum ACTH?
|
1. Primary addisions
2. Cushings disease 3. Ectopic ACTH syndrome 4. Stress 5. Congenital adrenal hyperplasia(inability to produce cortisol) |
|
|
What are 4 conditions that would reveal a decrease in serum ACTH?
|
1. Secondary adrenal insufficiency
2. Hypopituitarism 3. Adrenal adenoma/CA 4. STeroid administration |
|
|
What 2 types of cortisol does serum cortisol account for?
|
Bound and unbound = Total
|
|
|
When is serum cortisol lowest and when does it spike?
|
MN
Spikes at 6-8am |
|
|
What is sometimes the first sign of hyperfunction when testing serum cortisol?
|
The loss of diurnal variation.
|
|
|
Are cortisol and ACTH levels affected with night workers?
|
Yes, they switch. The normal values can be transposed on individuals who work nights.
|
|
|
How is serum cortisol testing carried out?
|
Explain procedure-rule out stressful situations.
Collect blood after good night's sleep in AM and then again at 4pm (NEED TWO) Indicate time of venipuncture |
|
|
What does urine cortisol testing test for - what type of test is used?
|
Unbound(Free) cortisol-because bound cortisol is not filtered by the kidney - at >25mcg/dL cortisol binding globulin becomes saturated and the unbound portion spills into urine
24 hour urine |
|
|
When performing urine cortisol testing, what else might be tested for to determine if you have a valid sample?
|
Creatinine
|
|
|
What are some factors that can interfere with serum/urine cortisol testing?
|
1. Pregnancy (increase level)
2. Stress (increase level) 3. Radioisotope scans 4. Drugs: Increase- Estrogen,OCs,amphetimines, cortisone, aldactone Decrease-Androgens,Danazol,Lithium, Levodopa, Metyrapone,Dilantin |
|
|
Abnormally increased plasma /urine cortisol levels could be a result of?
|
1. Cushings dz
2. Adrenal adenoma 3. Ectopic ACTH producing tumors 4. Hyperthyroidism 5. Obesity 6. Stress |
|
|
What are some conditions that could result in a low plasma/urine cortisol?
|
1. Addisons dz
2. Liver dz 3. Hypopituitarism 4. Hypothyroidism |
|
|
What is the Dexamethasone test based on?
|
Dexamethasone is a synthetic steroid(similar to cortisol)- and is based on the fact that pituitary ACTH secretion is dependent upon the plasma cortisol mechanism.
|
|
|
What DST is used to differentiate btwn normal and abnormal - screening?
|
1mg
|
|
|
What DST is used to differentiate btwn Cushings dz and Cushings syndrome?
|
8mg
|
|
|
What are some factors that can interfere with DST?
|
Physical or emotional stress
Drugs: Estrogens,OCP,Steroids, Dilantain,Spironolactone, Tetracycline |
|
|
What result do you expect with DST?
|
inhibition of ACTH and a 50% or more drop in plasma cortisol and urine cortisol levels.
|
|
|
How does the 1mg DST work?
|
Give 1mg at 11pm (with food to prevent gastric irritation).
-Maybe barbituate to help sleep Draw serum Cortisol sample at 8AM the next morning |
|
|
How does the 8mg DST work?
|
Do test again next night with 8mg of dexamethasone PO at 11pm (with food,barbituate, no stress)
Draw serum cortisol at 8am next morning. Pts with Cushing's dz may have >50% reduction in plasma cortisol. |
|
|
What results would you expect from DST in a pt with Cushings disease(Bilat adrenal hyperplasia)?
|
Low dose: No change
High dose: >50% decrease in plasma and urine cortisol |
|
|
What results would you expect from DST in a pt with Adrenal adenoma/carcinoma?
|
Low or high dose DST: no change
|
|
|
What results would you expect from DST in a pt with Ectopic ACTH-producing tumor?
|
Low or high dose DST: no change
|
|
|
What are 3 important points with DST'ing?
|
1. eval for gastric irritation throughout test
2. Assess steroid induced SEs by monitoring weight, glucose levels, and K levels 3. Ensure samples get to lab promptly |
|
|
What is ACTH stimulation testing with Cosyntropin?
|
Cosyntropin is a synthetic subunit of ACTH and has same corticosteroid stimulation effect as endogenous ACTH.
|
|
|
What is the expected result with ACTH stimulation testing with Cosyntropin?
|
After ACTH admin the adrenal gland responds by increased serum cortisol.
|
|
|
What are the 3 ways the ACTH stimulation testing with Cosyntropin is performed?
|
1. Rapid test
2. 24 hour test 3. 3-day test |
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What type of test is the ACTH stimulation testing with Cosyntropin Rapid test - response?
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A screening test only! Get baseline serum Cortisol and Aldosterone 30 minutes before Cosyntropin dose.
Give Cosyntropin over 2 min. Measure plasma Cortisol and Aldosterone at 30-60 minutes. Normal response: Appropriate increase in plasma cortisol - THIS EXCLUDES adrenal insufficiency. ABNL: Cushings or Addisions - further testing |
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How does the ACTH stimulation test with Cosyntropin when 24 hour testing work?
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Obtain baseline cortisol level - Admin IV Cosyntropin over 24 hours - Measure plasma cortisol at 24 hours
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How does ACTH stimulation test with Cosyntropin when 3 day testing work?
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Obtain baseline serum cortisol level. Admin Cosyntropin IV over 8 hours on 2-3 consecutive days. Measure plasma cortisol at 12,24,38,48,60,72 hours after start of test.
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If your ACTH stimulation test with Cosyntropin is normal, what next?
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Nothing, you are done.
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Does the 'Rapid' ACTH stimulation test with Cosyntropin with normal result R/O Addison's?
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Yes
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If the 'Rapid' ACTH stimulation test with Cosyntropin is abnormal and you suspect Addison's then how do you differentiate btwn primary and secondary dz?
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After giving Cosyntropin - if there is little response to ACTH = Primary adrenal insufficiency (adrenal dz); Aldosterone levels might be low too.
If there is minimal to increased response to ACTH think secondary adrenal insufficiency (pituitary cause)-Aldosterone levels should be unaffected. |
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Even though ACTH stimulation test with Cosyntropin, is not normally used with Cushings disease(bilat adrenal hyperplasia) what result would you expect?
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Increase in plasma cortisol following admin of ACTH (the adrenals have a exaggerated response to ACTH).
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Even though ACTH stimulation test with Cosyntropin, is not normally used with Cushings syndrome(Adrenal adenoma/CA,Ectopic tumor,Exogenous intake of steroids) what result would you expect?
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Either normal or NO change in plasma cortisol following ACTH admin.
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What is the ACTH stimulation test with Metyrapone?
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Metyrapone is a potent blocker of 11β-HSD(this enzyme involved in cortisol production). Blocking this enzyme causes cortisol production to fail- this normally should cause increased ACTH production.
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What is the procedure for ACTH stimulation testing with Metyrapone?
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Obtain baseline cortisol. Admin. 2-3 g of Metyrapone at 11pm. Collect serum cortisol and 11-deoxycortisol serum level at 8am.
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What is the procedure for ACTH stimulation testing with Metyrapone for the urine test?
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Obtain baseline 17-Hydroxycorticosteroid level.
Admin 500-750mg of Metyrapone every 4 hours for 24 hours. Collect 24 hour urine 17-OCHS(Cortisone precursor) during and 1 day after Metyrapone. |
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What pt population is the ACTH stimulation testing with Metyrapone not used in and why?
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Pts with Addison's dz. They could have an Addisonian crisis.
Muscle weakness, mental changes, anorexia, nausea, vomiting, hypotension, hyperkalemia, vascular collapse. THIS IS A MEDICAL EMERGENCY!!! Immediate treatment by replenishing steroids, reversing shock and restoring circulation. |
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Who do you use the ACTH stimulation testing with Metyrapone for?
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Cushings syndrome - differentiates btwn disease (pituitary adenoma) and cushing's syndrome(adrenal tumor,ectopic ACTH)
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What are the different results expected with ACTH stimulation testing with Metyrapone for Cushings dz and syndrome?
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1. In Cushing’s Disease-Serum/urine cortisol precursors RISE above normal because the normal adrenal/pituitary axis is intact.
2. In Cushing’s Syndrome (Adrenal adenoma/Ca or Ectopic ACTH)-there is NO change in serum/urine cortisol precursors because the tumors are autonomous cortisol producers and insensitive to changes in ACTH secretion 3. Secondary adrenal insufficiency: Loop not working so admin of Metyrapone does not change level of cortisol precursors. |
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What is inferior petrosal sinus sampling?
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This test is performed to differentiate btwn ectopic and pituitary adenomas - you cannulate the femoral v. into internal jugular and bilat placement into petrosal sinuses. Samples for measuring ACTH are collected from here and a peripheral vein at 0,3,5,10 after injection of CRH.
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What are the 3 samples taken with inferior petrosal sinus sampling?
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Peripheral, R and L inferior petrosal sinuses
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differentiate btwn ectopic and pituitary adenomas' results with inferior Petrosal Sinus sampling.
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Patients with ectopic ACTH syndrome have NO ACTH concentration gradient between the inferior petrosal sinus and the peripheral sample.
Patient’s with Cushing’s disease have an increased gradient of plasma ACTH between any or both of the inferior petrosal sinuses. |
