Chronic Kidney Disease USMLE Step 1 Practice Question
A 31-year-old woman presents with polyuria and intense polydipsia two weeks after transsphenoidal pituitary adenoma resection. Vital signs show HR 98/min, BP 138/82 mmHg, RR 16/min. Serum sodium is 151 mEq/L with serum osmolality of 310 mOsm/kg. Urine osmolality is 185 mOsm/kg. She denies recent medication changes and takes no diuretics. Following desmopressin administration, urine osmolality increases to 580 mOsm/kg. Which diagnosis best explains these findings?
Answer choices
- ANephrogenic diabetes insipidus
- BCentral diabetes insipidusCorrect answer
- CType 4 renal tubular acidosis
- DSyndrome of inappropriate antidiuretic hormone secretion
- EPrimary polydipsia
- FPituitary apoplexy with secondary adrenal insufficiency
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