Hyponatremia as a Presenting Sign for Sellar Masses

Introduction: Hyponatremia is a relatively rare presenting sign of sellar lesions. We present a series of patients who presented with hyponatremia leading to their diagnosis.

Method: All consecutive patients who presented from July 2007 to September 2012 with symptomatic hyponatremia as an initial presentation of their sellar mass were retrospectively analyzed for pituitary hormonal status, pathology, and treatment course.

Results: Eleven patients (five men and six women, age 31-87 years) presented with symptomatic hyponatremia (range, 101-128 mmol/L). Of these, three had two or more episodes of hyponatremia before their sellar lesion was diagnosed. Nine patients were found to have at least one pituitary axis dysfunction. Imaging and pathology confirmed six pituitary macroadenomas (maximal diameter: 17-31 mm; 5 endocrine-inactive and 1 functional, 3 with apoplexy), two arachnoid cysts (maximal diameter: 27 and 35 mm), two Rathke’s cleft cyst (maximal diameter: 10 and 14 mm; one with apoplexy), and one hemangioblastoma (maximal diameter: 30 mm). After correction of hyponatremia, all patients underwent uncomplicated endonasal surgery. Serum sodium levels ranged from 132-145, 131-146, and 137-145 mmol/L on postoperative days 1, 2, and 4, respectively. No recurrent bouts of hyponatremia were documented. At 3 months or more after surgery, hormonal status was stable or improved in 10 patients; 1 with apoplexy developed diabetes insipidus requiring DDAVP. No patients with craniopharyngiomas presented with hyponatremia during the study period.

Conclusion: Patients presenting with new onset symptomatic hyponatremia without a clear etiology should undergo an endocrine workup and sellar imaging.