What is diabetes insipidus?

What is diabetes insipidus?

The most common endocrine dysfunction postopera-tively is diabetes insipidus (DI). The dilute polyuria of cen-tral DI is caused by diminished or absent antidiuretic hormone (ADH) synthesis or release. Neurosurgical proce-dures in the region of the sella result in DI for a variety of reasons: direct hypothalamic injury or ischemia; stalk edema; or high pituitary stalk dissection. 

DI may be per-manent or transient and rarely occurs intraoperatively in previously asymptomatic patients. Classic manifestations of DI are polydipsia and a high output of poorly concen-trated urine despite increased serum osmolarity. DI that develops during or immediately after pituitary surgery is generally due to reversible trauma to the posterior pitu-itary and is therefore transient.

The differential diagnosis includes diuresis from man-nitol, glucose, or excessive crystalloid administration. Initial treatment of DI consists of intravenous infusion of electrolyte solutions if oral intake cannot offset polyuria. When urinary volumes are excessive and the patient is unable to drink water, the administration of exogenous vasopressin is indicated. Aqueous vasopressin, 5–10 U, can be given subcutaneously every 4 hours. Alternatively, desmopressin (DDAVP) can be administered intravenously while the nasal packing is in place, and intranasally once the nasal packing is removed. Desmopressin therapy can be pre-scribed in patients with permanent, partial or complete DI.