Electrolyte Disorders USMLE Step 1 Practice Question
A 54-year-old man with chronic alcoholism is admitted for severe hyponatremia after several days of poor food intake while drinking large quantities of beer. Laboratory studies show sodium 118 mEq/L, serum osmolality 250 mOsm/kg, urine sodium 8 mEq/L, and urine osmolality 85 mOsm/kg. Which of the following is the most likely mechanism of his hyponatremia?
Answer choices
- ASevere hypertriglyceridemia causing pseudohyponatremia
- BNephrogenic syndrome of inappropriate antidiuresis
- CExcess ADH secretion due to lung cancer
- DLow solute intake limiting free water excretionCorrect answer
- EPrimary adrenal insufficiency
- FThiazide diuretic use causing increased renal sodium wasting
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