Acid-Base Disorders USMLE Step 1 Practice Question
A 61-year-old man with advanced chronic kidney disease presents with fatigue and anorexia. Vital signs show BP 158/92 mmHg, HR 88/min, RR 22/min, temperature 37.1°C, and SpO2 98% on room air. He has bilateral lower extremity edema but denies dyspnea. Laboratory studies reveal BUN 88 mg/dL, creatinine 7.2 mg/dL, Na+ 139 mEq/L, Cl− 101 mEq/L, and HCO3− 14 mEq/L. Which acid-base disorder best explains these findings?
Answer choices
- AExcess aldosterone activity
- BHyperventilation from anxiety
- CLoss of bicarbonate in stool
- DHydrogen ion loss from the stomach
- EAccumulation of unmeasured organic anionsCorrect answer
- FImpaired renal excretion of phosphate and sulfate
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