Acid-Base Disorders USMLE Step 1 Practice Question
A 34-year-old woman presents with 2 days of profuse diarrhea after returning from a camping trip. Vital signs show BP 98/62 mm Hg, HR 108 bpm, RR 22/min, temperature 37.2°C, and SpO2 98% on room air. She appears dehydrated with dry mucous membranes. Arterial blood gas reveals pH 7.28, PaCO2 30 mm Hg, HCO3− 14 mEq/L, and serum electrolytes show normal anion gap. She denies vomiting. Which of the following best describes her respiratory status?
Answer choices
- APrimary respiratory alkalosis with renal compensation
- BSuperimposed respiratory alkalosis
- CMixed metabolic alkalosis and respiratory acidosis
- DAppropriate respiratory compensationCorrect answer
- ESuperimposed respiratory acidosis
- FPrimary metabolic alkalosis with inadequate respiratory response
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.