TRANSIENT DIABETES INSIPIDUS

A COMPLICATION FOLLOWING TRANS- SPHENOIDAL SURGERY

Abstract

BACKGROUND
Central diabetes insipidus (DI) is one of the complications of trans-sphenoidal surgery caused by the damage of vasopressin-secreting neurons. While some patients develop permanent DI, most patients fully recover.

CASE
A 26-year-old female was referred to the endocrinology clinic for a suprasellar tumor. She presented with a chief complaint of hemianopsia two months prior to the admission. She also noted amenorrhea for about six months. Physical examination only showed bitemporal hemianopsia. She had normal free T4, TSH, LH, FSH, and cortisol levels. Brain MRI revealed cystic pituitary macroadenoma in the sellar-suprasellar region with optic chiasm compression. A day following transphenoidal surgery, she experienced polydipsia and polyuria. The patient was treated with desmopressin which improved symptoms in two days. After discontinuing desmopressin, her urine volume remained within normal limits.

DI as a complication of trans-sphenoidal surgery occurs in 18 to 30%, but the risk factors are not well established. It can be transient, permanent or triphasic, depending on the damage of vasopressin-secreting neurons. Postsurgical DI is diagnosed by excluding other forms of polyuria, such as excess intravenous fluids or mannitol administration. Key diagnostic clues are increased thirst, hypotonic polyuria and hypernatremia and/or hyperosmolality. Majority of cases are transient and resolve after two to three doses of desmopressin.

CONCLUSION
Urinary excretion and water balance following trans- sphenoidal surgery should be monitored closely. Increased diuresis might indicate postsurgical DI despite the amount of intravenous fluid administration.