Acid-Base Disorders USMLE Step 1 Practice Question
A 24-year-old woman with a 3-day history of severe vomiting from gastroenteritis presents with generalized weakness and muscle cramps. Vital signs: BP 108/62 mmHg, HR 98 bpm, RR 16/min, Temp 37.2°C, SpO2 98% on room air. Laboratory studies reveal pH 7.52, PCO2 48 mmHg, HCO3− 38 mEq/L, K+ 2.8 mEq/L, Cl− 88 mEq/L. Urine chloride is low. Which acid-base disorder best explains these findings?
Answer choices
- AMetabolic acidosis with respiratory alkalosis
- BMixed metabolic and respiratory alkalosis
- CRespiratory alkalosis with metabolic compensation
- DRespiratory acidosis with metabolic alkalosis
- EMetabolic alkalosis with appropriate respiratory compensationCorrect answer
- FPrimary respiratory alkalosis with concurrent hypokalemic metabolic acidosis
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