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LECT_1
ECF and plasma tonicity
Question | Answer |
---|---|
Low Plasma [Na] and low plasma Osm | Check urine osmolarity |
Cause of pseudohyponatremia? | high triglycerides, high protein |
low urine osmolality (<100) with hyponatremia | psychogenic polydipsia |
high urine osmolality (>100) with hyponatremia | def. in renal dilution (ABNL high ADH) |
Causes of euvolemic hyponatremia? | SIADH! GC def., hypothyroidism, drugs, tumor |
low ECF with hyponatremia | VOL. DEPL: Diarrhea, diuretics, MC def. |
NL ECF with hyponatremia | edematous disorders |
hypertonic challenge with hypoVOL | water loss - diarrhea/vomiting; skin loss; kidney (osm. diur.) |
euvolemic hypertonicity | pure water loss - DI (central/nephrogenic) |
hypervolemic hypertonicity | iatrogenic (hypertonic solutions); salty foods |
correcting hyponatremia | concentration raised at the rate that it falls; Rapid correction - no more than 12 mEq/L/24hr |
hyponatremia correction EQUATION | Na/hr = <delta>[Na]/hr x TBW |
hypernatremia correction | SLOWLY: half-correction in 24hr period TBW(present)*[Na](present) = TBW(nl) * [Na](nl) |