Acid-Base Disorders USMLE Step 1 Practice Question
A 36-year-old woman presents with chronic watery diarrhea due to inflammatory bowel disease. She has pH 7.30 and serum bicarbonate 16 mEq/L. Her physician wants to distinguish extrarenal bicarbonate loss from renal tubular acidosis. Which of the following additional findings would be most consistent with diarrhea as the cause of her metabolic acidosis?
Answer choices
- AHyperkalemia due to low aldosterone
- BCalcium phosphate kidney stones
- CNegative urine anion gapCorrect answer
- DPositive urine anion gap
- EUrine pH persistently above 5.5
- FElevated serum chloride concentration relative to sodium
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