Electrolyte Disorders USMLE Step 1 Practice Question
A 55-year-old man with a 10-year history of alcoholic cirrhosis and refractory ascites presents to the hospital with a 3-day history of progressive muscle cramps, generalized weakness, and disorientation. He has been taking furosemide 80 mg daily and spironolactone 50 mg daily for ascites management. On examination, he is alert but confused, with mild asterixis. Vital signs: BP 108/62 mmHg, HR 102/min, RR 16/min, temperature 37.0°C. Laboratory studies show: sodium 125 mEq/L, potassium 2.8 mEq/L, chloride 85 mEq/L, bicarbonate 32 mEq/L, arterial pH 7.48, PCO2 38 mmHg, PO2 92 mmHg on room air. Serum creatinine is 0.9 mg/dL (baseline 0.8 mg/dL). Urine chloride is 15 mEq/L. Which of the following acid-base disturbances is most likely responsible for this patient's mental status changes?
Answer choices
- AMetabolic acidosis with appropriate respiratory compensation
- BRespiratory alkalosis with concurrent metabolic acidosis
- CMetabolic alkalosis with concurrent respiratory alkalosis
- DMetabolic alkalosis with inadequate respiratory compensationCorrect answer
- ERespiratory acidosis superimposed on metabolic alkalosis
- FPure respiratory alkalosis from hepatic encephalopathy
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