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27 Cards in this Set
- Front
- Back
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Hyponatremia - DDX - misidiagnose SIADH
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Pt on diuretics & has reflex water retention
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SIADH - Dx criteria
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euvolemia
urine na >20 mmol/L normal renal fx no diuretics adrenal gland ok |
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Pseudohyponatremia
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Urine osm >280 because of hyperglycemia, hyperlipidemia, hyperproteinemia
Normal serum osms, measure with indirect ISE, not seen when measure with direct ISE |
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5 major mechanisms for hyponatremia
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With normal serum osmolality - pseudohyponatremia & osmotic dilution these are least common
Decreased serum osms - most common - sodium wasting, excess water, edema |
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Osmotic fluid shifts
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osmotically acitve substance in plasma
glucose, mannitol, glycine(TURP, endometrial ablation) |
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Na Wasting
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renal or extrarenal losses
lost fluid has normal osms but stimulates thirst & ADH so increased water will decrease Na. Pt is hypovolemic Renal losses - diuretics, medullary disease, Addisons, RTA type I, diuretics (Urine NA >30) Extrarenal losses - skin (fever, sweating) or GI diarrhea - U Na is <30) |
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Excess water
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Pt is euvolemic
SIADH (CNS d/o, pulmonary d/o, malignancy, medication (psychiatric) Excess water ingestions - psychogenic polydypsia Ecstasy |
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Edematous States
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CHF, nephrotic syndrome, cirrhosis
(intravascular volume is low - stimulate thirst & ADH - increase free water) |
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Hypernatremia
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Loss of Na & Water
Replace only water Defective Thirst Mechanisms (dementia, lack of water access, ) Rare - hypertonic solutions |
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Hypernatremia caused by DI & hyperaldosteronism
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No - because thirst mechanisms work
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Normal Fluid Compartments
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Body - 60% water
60% intracellular, 40% extracellular (10% intravascular, 30% interstitial) |
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daily fluid loss
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1.5-2.0 L lost daily, 1L insensible water loss
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3 mechanisms to prevent net fluid loss
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1. Thirst
2. ADH 3.Renin Aldosterone - decreased tubular blood flow or decreased Na delivery |
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ANP/BNP
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respond to cardiac stress, inhibit renin, promote renal Na excretion
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indirect Ion Selective Electrodes (ISE)
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measure Na or K in dilute solutions -
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direct Ion Selective Electrodes (ISE)
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measure Na in undiluted solutions
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Serum osmolality
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1. calculation
2. measure freezing point depression (esp when you want to detect alchols) 3. measure vapor pressure elevation (will not detect alcohols) |
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Urine sodium excretion
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1. calculation
2. Maximally resorbed <0.5% 3. Wasted - often is >3% |
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Urine Osmolality
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renal concentration in the patient
1.Indicates state of ADH 2.Excess water - <50 3. ADH produced >900 |
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Hypokalemia
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Increased K excretion - diuretics, hyperaldosteronism, RTA I & II, low Mg,
GI tract - vomiting, fistula, diarrhea, NGT, villous adenoma Decreased intake - starvation Intracellular shifts - correction of DKA, alkalosis, refeeding |
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Hyperkalemia
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Artifactual - #1,
Decreased renal excretion Shifting K out of cells Increased K ingestion |
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Hyperkalemia - artifactural
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Delayed separation
Hemolysis Fist clenching Drawing near IV with K EDTA Inc Plts Inc Lymphs Familial pseudohypekalemia, CH16 |
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Renal tubular acidosis I & II are associated with hyperkalemia.
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False - they are associated with hypokalema RTA type IV is associated with hyperkalemia
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Hyperkalemia- decreased renal excretion
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Renal Failure
hypoaldosteronism Drugs blocking renin/aldo (ACEI, NSAIDS) K sparing diuretics RTA type IV |
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Hyperkalemia - cellular shift
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Hemolysis
low insulin tumor lysis rhabdomyolysis |
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Hyperkalemia - inc intake
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salt substitute
Neutrophos, PVK |
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Hypokalema
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Increased K excretion
Kidneys (diuretics, hyperaldosteronism, RTA, Mag deficiency) GI loss (vomiting, fistula, diarrhea) Decreased intake (starvation) Intracellular shifts (refeeding, correcting DKA, alkalosis) |
