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69 Cards in this Set
- Front
- Back
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Symptoms of hypoglycemia can be classified into two types of responses: Fasting or Reactive
What is the cause of each? |
Fasting: caused by brain hypoglycemia, not rapid in onset
Reactive: caused by adrenergic activity, tends to be rapid |
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How do the symptoms differ in reactive vs. fasting hypoglycemia?
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Fasting: mental status changes
Reactive: sweating, tachycardia, nervousness |
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What are 4 different drugs that can induce hypoglycemia (classes, not specifics)?
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Alcohol, sulfonylureas and other oral hypoglycemics, insulin, and quinine
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What is nesidioblastosis?
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islet Beta cell proliferation
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What is Whipple's triad and what is it associated with?
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plasma glucose <45mg/dL, hypoglycemic changes, and correction of symptoms by glucose administration
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In a patient with a suspected insulinoma, what do you expect the insulin level to be?
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The absolute insulin level may actually be normal, but will be inappropriately high for the degree of hypoglycemia. Or it might be high.
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What should the insulin:glucose ration be in insulinoma?
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>180
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What are some causes of reactive hypoglycemia?
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The abnormal rapid-onset hypoglycemia following a meal can be caused by heriditary fructose intolerance, galactosemia, dumping syndrome (post vagotomy), rarely early type 2 diabetes
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Pancreatic islet cells secrete what two substances in equimolar amounts?
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Insulin and C-peptide
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Which substance secreted by pancreatic islet cells is metabolized faster?
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Insulin is metabolized faster than c-peptide.
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What is the primary clinical use of C-peptide?
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Since it hangs around so much longer than insulin but is secreted in equal amounts you can determine if insulin is being naturally released or exogenously administered.
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What is the shortcoming in using the C-peptide to evaluate for exogenous administration of insulin?
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Renal failure impedes C-peptide clearance and will result in elevated C-peptide levels
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How can proinsulin be used clinically?
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Proinsulin should represent less than 10% of the insulin level, so an elevated level may represent insulinoma
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Anti-insulin antibodies can be seen in what 3 clinical settings?
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Administration of insulin produces (rare), autoimmune insulin syndrome, and rarely insulinoma (actually all of these are rare)
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What is the cause of hypoinsulinemic hypoglycemia?
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Too much insulin (insulinoma or exogenous)
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What are the two types of hyperinsulinemic hypoglycemia?
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Ketotic and non-ketotic
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Non-ketotic hypoglycemia suggests what clinical settings?
How about ketotic hypoglycemia? |
presence of insulin-like activity such as in autoimmune hypoglycemia, starvation, liver failure
Ketotic: all other causes |
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Since insulinoma may be associated with MEN1, what additional test should be performed?
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Serum calcium (remember PTH adenomas?)
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How can you diagnose hypoglycemia after death?
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Virtually impossible
You can detect insulin, peptide C, and proinsulin for several days after death |
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What is the cause of Type 1 diabetes?
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autoimmune destruction of islet B cells
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What percentage of diabetics are type 1?
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~10%
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T/F
Autoantibodies are not part of the clinical picture in Type I Diabetes |
False
anti-GAD65, anti-ICA512, Anti-IAA can each be present |
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What is the cause of Type 2 Diabetes?
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progressive insulin resistance with subseuent burn-out of islet cells
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What is the recommeded test to diagnose diabetes in nonpregnant persons?
What is the diagnostic level? |
Fasting plasma glucose
> or = 126 mg/dL is considered diagnostic |
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A 60yo obese man presents with frequent urination, recent weight loss, poorly healing wounds, and fatigue. You suspect diabetes, however he has eaten breakfast that morning and a fasting glucose cannot be performed. What can you do?
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A random plasma glucose of >200mg/dL with symptoms of diabetes is diagnostic
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What is the diagnostic level for diabetes with the oral glucose tolerance test?
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75g of glucose is given and a 2 hour reading is taken. >200 mg/dL is diagnostic.
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What fasting plasma glucose level is defined as "impaired fasting glucose/pre-diabetic"
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99mg/dL
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What is the diagnostic level in the glucose tolerance test for "Impaired glucose tolerance"/prediabetes
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>139mg/dL at 2 hours after 75 grams
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How is the gestational diabetes oral glucose tolerance test different than the normal fasting glucose tolerance test?
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The amount of glucose is different
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What types of women can avoid glucose tolerance testing totally?
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young (<25y), healthy, normal pre-pregnancy weight, low-risk ethnicity, no family history and no prior OB complications
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What is the earliest screening for high risk women for GDM?
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a fasting plasma glucose (>126mg/dL) is diagnostic
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Non-high risk women and high risk women who "pass" their first screening should undergo what test next?
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At 24-28 weeks they should have a 100g load oral glucose tolerance test.
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What are the criteria for a positive 100g OGTT?
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Need two of the following:
>95 mg/dL fasting >180 mg/dL 1hour >155 mg/dL 2 hour >140 mg/dL 3 hour |
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Often, women are "pretested" before undergoing the full 3 hour/100g OGTT? What does this consist of?
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a 50g 1 hour OGTT: A measurement of >140mg/dL at one hour necessitates the 3 hour test.
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A 28 year-old woman is diagnoses with gestational diabetes and goes on to deliver a (large) healthy baby with no complications. What additional followup does mom need?
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Testing for GDM at 6-12 weeks postpartum
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Should the HbA1c test be used for diabetes diagnosis?
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NO
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What does the HbA1c test monitor?
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Long term glycemic control
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What is the American Diabetes Association recommended goal of therapy level of HbA1C?
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<7%
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Name 4 other lab values that are important to check in diabetics?
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Lipid disorders, microalbunemia, serum creatinine for estimated glomerular filtration rate, hypomagnesemia
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Who gets diabetic ketoacidosis?
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Insulin-dependent diabetics
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What are the 3 usual requirements for the diagnosis of DKA?
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hyperglycemia (>200mg/dL), ketosis, metabolic acidosis (venous pH < 7.3 or bicarb less than 15mmol/L)
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What are the urinalysis findings usually seen with DKA?
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glycosuria and ketonuria
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T/F: DKA is often associated with leukopenia.
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False. DKA is often associated with neutrophilia (that is not necessarily infectious in nature--unknown mechanism) But remember--DKA can be prompted by infection
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What are the three major serum ketones in DKA?
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acetone, acetoacetic acid, B-hydroxybutyrate
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What laboratory technique is used for measuring ketones?
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nitroprusside technique sensitive to acetone and acetoacetic acid but not B-hydroxybutyrate.
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What is the shortcoming in our laboratory analysis of ketones?
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Our nitroprusside technique measures only acetone and acetoacetic acid which accounts for only 20% of the serum ketones. B-hydroxybutyrate is converted to the other two measurable forms during treatment, so an apparent "bump" might be seen in the lab levels even with successful treatment
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What do you expect glucose level to be in DKA?
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>200mg/dL
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Is bicarbonate decreased or increased in DKA?
Is pH decreased or increased in DKA? |
Bicarb is down, pH is down (acidosis)
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Why is Potassium elevated in DKA?
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The Potassium is extracellular with the low pH, but the urinary excretion is increased, so true body potassium can be very LOW. When given insulin, the potassium can shift very quickly.
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What is the typical BUN level during DKA?
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increased due to severe volume depletion resulting in prerenal azotemia.
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Which patients get Hyperglycemic hyperosmolar nonketotic coma?
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Type 2 (non-insulin dependent) diabetics
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Which is more common, DKA or HHNC?
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DKA
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Which has higher mortality, DKA or HHNC?
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HHNC
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What is the typical glucose level in HHNC?
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at least 600mg/dL (may be >1000!)
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What is the typical osmolarity in HHNC?
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>330 mOsm/L
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What is the pH/Bicarb level in HHNC?
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normal
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What is the ketone level in HHNC?
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normal
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What is the potassium level in HHNC?
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may be elevated with true total body deficit (as in DKA)
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What is the BUN level in HHNC?
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Very elevated secondary to dehydration
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What is Syndrome X?
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Metabolic syndrome, the insulin resistance syndrome referring to the cluster of hyperlipidmia, impaired glucose tolerance, central obesity, increased CRP, HTN--association with cardiac disease
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Why is it not cost-effective to screen for cancer with tumor markers?
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The sensitivity of a test is dependent on the prevelence in the population, thus if you screen everyone you negate the good points of the test
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What is the "Hook effect" in immunoassay?
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When very high concentration overwhelm binding capacity of both capture and signal antibodies, thus yielding a low or even negative result.
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Why is the Hook effect a concern in tumor marker testing?
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Widely metastatic disease can have super high tumor marker levels, and lead to the Hook effect
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How can you adjust for the Hook effect?
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Perform the assay at multiple dilutions
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What are heterophile antibodies?
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Antiblodies that may be present in the patient that have wide reactivity with antibodies of other species.
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How can one adjust for heterophile antibodies?
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heterophile blocking reagents, remove immunoglobulins, serial dilutions
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What are other situations that may show elevated PSA (besides cancer)?
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BPH, prostatitis, prostatic infarct, and following needle biopsy of the prostate
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What is the level of PSA that, beyond which, is rarely associated with benign disease?
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10ng/mL--above this level you will typically not see a benign process
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What is the approximate percentage of men that will be found to have prostatic carcinoma with elevated PSA (>4.0 ng/mL)?
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30-40% of men
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