Acid-Base Disorders USMLE Step 1 Practice Question
A 24-year-old woman presents with severe vomiting for 3 days following gastroenteritis. Vital signs: BP 110/70 mmHg, HR 105 bpm, RR 16, temp 37.2°C, SpO2 98% on room air. Labs show pH 7.48, PCO2 48 mmHg, HCO3− 36 mEq/L, K+ 2.8 mEq/L, Cl− 88 mEq/L. She denies aspirin use. Urine chloride is low. Which acid-base disturbance best explains her clinical presentation?
Answer choices
- AMetabolic alkalosis with respiratory compensationCorrect answer
- BRespiratory acidosis with concurrent hypokalemia
- CPrimary hyperventilation syndrome
- DMixed metabolic and respiratory alkalosis
- EPrimary respiratory alkalosis with metabolic compensation
- FMetabolic acidosis with secondary hyperventilation
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