A 38-year-old woman, on the first postoperative day after transsphenoidal pituitary adenomectomy, passes 400 mL of dilute urine hourly for 3 consecutive hours. Serum sodium is 153 mEq/L, plasma osmolality 310 mOsm/kg, and urine osmolality 110 mOsm/kg. Which is the MOST appropriate next step?

• A Fluid restriction and close observation
• B Furosemide 40 mg intravenously
• C Intravenous desmopressin ✓
• D Isotonic saline at maintenance rate

Explanation

Polyuria with hypernatraemia, high plasma osmolality and inappropriately dilute urine defines central diabetes insipidus, the commonest endocrine complication of transsphenoidal surgery, typically appearing 12 to 48 hours postoperatively. Treatment is desmopressin with free water replacement. Fluid restriction is dangerous in established DI with rising sodium, and furosemide would worsen both polyuria and hypernatraemia.

Reference: Greenberg's Handbook of Neurosurgery, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.