Predictive Factors for Delayed Hyponatremia After Endoscopic Transsphenoidal Surgery in Patients with Nonfunctioning Pituitary Tumors: A Retrospective Observational Study.

Objective Delayed hyponatremia can occur after transsphenoidal pituitary tumor surgery, resulting in unexpected readmission. Predictive factors for delayed hyponatremia after this type of surgery are not well established. In this retrospective study, predictive factors for delayed hyponatremia were investigated in patients undergoing transsphenoidal pituitary tumor surgery. Methods Preoperative data (demographics, comorbidities, and hormonal assessment), preoperative, intraoperative, and immediate postoperative sodium concentrations, the nadir sodium concentration on postoperative day (POD) 1–2, characteristics of pituitary tumor (size, cell type, optic chiasm compression, and cavernous sinus invasion), and intraoperative data (operation time and fluid balance) were retrospectively collected from 234 patients undergoing endoscopic transsphenoidal surgery for removal of nonfunctioning pituitary tumors. Delayed hyponatremia was defined as serum sodium concentration <135 mEq/L on POD 3 or later, and after discharge, postoperative sodium concentration was measured on POD 7–10. Results Delayed hyponatremia was observed in 53 patients (22.6%). Of these patients, 5 (9.4%) were readmitted because of delayed hyponatremia. In binary logistic regression analysis, age >60 years (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.16–4.26; P = 0.017), the nadir sodium concentration on POD 1–2 (OR, 0.88; 95% CI, 0.77–0.99; P = 0.034), and operation time (OR, 1.01; 95% CI, 1.00–1.02; P = 0.018) were independent risk factors for delayed hyponatremia after endoscopic transsphenoidal pituitary surgery. Conclusions The incidence of delayed hyponatremia in patients with nonfunctioning pituitary tumor who underwent endoscopic transsphenoidal surgery was 22.6%. Old age, low sodium concentration on POD 1–2, and long operation time were associated with the development of delayed hyponatremia in such patients. [ABSTRACT FROM AUTHOR]