Diabetes Insipidus (DI)

Track urine output and sodium - Large dilute urine output with a rising sodium signals DI; monitor closely, especially after pituitary or neurosurgical procedures and in head injury.

Fluid replacement - Replace the free-water deficit and ongoing losses to prevent hypernatremia and hypovolemia; match input to the massive output.

Desmopressin for central DI - Central DI responds to DDAVP; continue the patient's regimen and treat new-onset central DI with it. Nephrogenic DI does not respond to DDAVP.

Avoid sodium swings - Correct hypernatremia at a controlled rate; rapid shifts are harmful.

Perioperative vigilance - New DI can appear intraoperatively or postoperatively after relevant surgery — keep watching output and electrolytes.

Diabetes insipidus is the inability to concentrate urine, from deficient antidiuretic hormone (central DI — pituitary or hypothalamic, common after neurosurgery or head injury) or renal resistance to it (nephrogenic DI).

The result is large volumes of dilute urine and, if intake can't keep up, hypernatremia and hypovolemia. Perioperatively — especially around pituitary and neurosurgery — DI can appear abruptly, and the anesthetist must track urine output and sodium closely and replace both water and, in central DI, desmopressin.