Pituitary Disorders USMLE Step 1 Practice Question
A 28-year-old man with acromegaly and elevated IGF-1 (680 ng/mL) undergoes transsphenoidal resection of a growth hormone-secreting pituitary adenoma. Postoperatively, he develops polyuria and polydipsia. Vital signs show BP 118/76, HR 92, RR 16, temp 37.2°C. Serum osmolality is 298 mOsm/kg with urine osmolality of 95 mOsm/kg despite adequate fluid intake. Morning cortisol remains normal. Which of the following best explains this complication?
Answer choices
- ACentral diabetes insipidus from ADH deficiencyCorrect answer
- BHypernatremia from excessive saline administration
- CNephrogenic diabetes insipidus from hyperglycemia
- DPsychogenic polydipsia from surgical stress
- ESyndrome of inappropriate antidiuretic hormone secretion
- FOsmotic diuresis from postoperative hyperglycemia
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