Postoperative Hyponatremia After Endoscopic Endonasal Resection of Pituitary Adenomas: Historical Complication Rates and Risk Factors

Background: Hyponatremia is a common complication following endoscopic endonasal resection (EER) of pituitary adenomas. We report a single-center, multisurgeon study detailing baseline clinical data, outcomes, and factors associated with postoperative hyponatremia. Methods: This was a retrospective cohort study of patients undergoing EER for pituitary adenoma at Tufts Medical Center. Most procedures were performed by the senior author (C.B.H.). Cases were included if at least 1 postoperative sodium value was available and pathology confirmed pituitary adenoma. Hyponatremia was defined as a postoperative sodium level <135 mEq/L. Results: A total of 272 patients underwent 310 EER procedures that met the study inclusion criteria. The mean patient age was 53.3 years, and mean tumor size was 18.8 mm. Postoperative hyponatremia occurred in 12.6% of cases, with 3.6% developing hyponatremia prior to discharge. Lower preoperative sodium level was associated with an increased risk of developing any postoperative hyponatremia. Older age, prolactinoma pathology, and use of selective serotonin reuptake inhibitors were associated with moderate to severe hyponatremia (<= 129 mEq/L), and lower preoperative sodium was associated with mild hyponatremia (130-134 mEq/L). Hyponatremia-related readmissions within 30 days occurred in 3.9% of patients. Both African-American race and postoperative hyponatremia were associated with an increased risk of 30-day readmission. The mean nadir sodium for hyponatremic patients was 129.9 mEq/L. Growth hormone-secreting pathology was associated with lower postoperative nadir sodium, whereas higher preoperative sodium was associated with higher postoperative nadir sodium. Conclusions: Hyponatremia is a common postoperative complication of EER for pituitary lesions that can cause significant morbidity, increased readmissions, and increased healthcare costs.