Diabetes insipidus following resection of pituitary tumors.

Diabetes insipidus (DI) is a common complication following pituitary surgery and can be transient or permanent. Neurogenic DI occurs following injury to the magnocellular neurons in the hypothalamus that produce and transport arginine vasopressin (AVP) and form the hypothalamo-hypophyseal tract. DI is defined by a constellation of signs and symptoms resulting in dilute high-volume urine output and increasing serum osmolality. The body's inability to concentrate urine leaves the patient dehydrated and leads to metabolic abnormalities that can be life threatening if not recognized and treated in a timely manner with an exogenous AVP analog. The reported incidence of postsurgical central DI varies from 1 to 67%. This wide range likely reflects inconsistencies in the working definition of DI across the literature. Factors affecting the rate of DI include pituitary tumor size, adherence to surrounding structures, surgical approach, and histopathology of pituitary lesion. The likelihood of postoperative DI can be reduced by careful preservation of the neurovascular structures of the hypothalamus, infundibulum, and neurohypophysis. Vigilance and meticulous surgical technique are essential to minimize injury to these critical regions that can lead to postsurgical DI.