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Central diabetes insipidus — ABIM Board MCQ

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ModerateEndocrinology/MetabolismCentral diabetes insipidusABIM Board

A 38-year-old develops intense thirst and polyuria after transsphenoidal pituitary surgery. Sodium is 152 mEq/L, serum osmolality is high and urine is dilute. Urine osmolality rises markedly after desmopressin. What is the diagnosis?

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Correct answer: C — Central arginine-vasopressin deficiency after pituitary surgery

The best answer is “Central arginine-vasopressin deficiency after pituitary surgery”. Pituitary surgery can impair vasopressin release, causing hypernatremia with inappropriately dilute urine. A marked concentration response to desmopressin localizes the defect to deficient hormone secretion. Nephrogenic disease responds poorly, primary polydipsia usually lowers serum sodium, and SIADH produces concentrated urine.

Reference: Endocrine Society Clinical Practice Guideline Resources for Pituitary Disorders: https://www.endocrine.org/clinical-practice-guidelines/pituitary-incidentaloma