Electrolyte Disorders USMLE Step 1 Practice Question
A 28-year-old man presents with progressive muscle weakness after several days of vomiting from viral gastroenteritis. Blood pressure is 96/60 mm Hg. Laboratory studies show sodium 138 mEq/L, potassium 2.7 mEq/L, chloride 86 mEq/L, bicarbonate 35 mEq/L, and urine chloride 8 mEq/L. Which of the following best explains his acid-base and electrolyte profile?
Answer choices
- AGastric hydrogen and chloride loss with secondary renal potassium wastingCorrect answer
- BLactic acidosis from hypoperfusion
- CPrimary hyperaldosteronism causing sodium retention
- DSIADH causing water retention and concentrated urine
- EDiarrheal bicarbonate loss with secondary hyperkalemia
- FRenal tubular acidosis with impaired ammonia excretion
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