Prevalence, predictors and patterns of postoperative polyuria and hyponatraemia in the immediate course after transsphenoidal surgery for pituitary adenomas

OBJECTIVE Disturbances of osmoregulation, leading to diabetes insipidus and hyponatraemia are well known complications after surgery in the sella regi on, This study was performed to examine the prevalence and predictors of po lyuria and hyponatraemia after a complete and selective removal of pituitar y adenomas was attempted via the transnasal-transsphenoidal approach. DESIGN 1571 patients with pituitary adenomas (238 Gushing's disease, 405 ac romegaly, 534 hormonally inactive adenomas, 358 prolactinoma, 23 Nelson's s yndrome, and 13 thyrotropinoma) were daily examined within a 10-day postope rative inpatient observation period. Prevalence of patterns of polyuria (> 2500 mi) and oliguria/hyponatraemia (<132 mmol/l) were surveyed as well as predictors of postoperative morbidity, RESULTS 487 patients (31%) developed immediate postoperative hypotonic poly uria, 161 patients (10%) showed prolonged polyuria and 37 patients (2.4%) d elayed hyponatraemia, A biphasic (polyuria-hyponatraemia) and triphasic (po lyuria-hyponatraemiapolyuria) pattern was seen in 53 (3.4%) and 18 (1.1%) p atients, respectively. Forty-one patients (2.6%) displayed immediate postop erative (day 1) hyponatraemia, Altogether, 8.4% of patients developed hypon atraemia at some time up to the 10th day postoperative, with symptomatic hy ponatraemia in 32 patients (2.1%). Risk analysis showed that patients with Gushing's disease had a fourfold higher risk of polyuria than patients with acromegaly and a 2.8-fold higher risk for postoperative hyponatraemia, You nger age, male sex, and intrasellar expansion were associated with a higher risk of hypotonic polyuria, but this was not considered clinically relevan t, CONCLUSIONS The analysis illustrates that disturbances in osmoregulation re sulting in polyuria and pertubations of serum sodium concentration are of v ery high prevalence and need observation even after selective transsphenoid al surgery for pituitary adenomas, especially in patients with Gushing's di sease.