OBJECTIVE

Hyponatremia is a known but underrecognized presentation of sellar lesions. Herein, we present a series of patients who presented with single or multiple episodes of hyponatremia.

METHODS

Over 5 years, patients undergoing endonasal surgery for a de novo sellar mass with hyponatremia as an initial presentation were included. Pathology, sodium levels, pituitary hormonal status, and treatment course were documented.

RESULTS

Of 282 patients, 16 (5.7%) (9 males, 7 females, age 32 to 84 years) presented with severe hyponatremia, with a mean serum sodium level of 115 ± 6 mmol/L (range, 101 to 125 mmol/L), and 3 patients had 2 or more episodes. Severe hyponatremia was a presenting sign in 0, 4.1, 14.3, and 37.5% of patients with craniopharyngiomas (n = 10), pituitary adenomas (n = 243), Rathke's cleft cysts (RCCs) (n = 21), and sellar arachnoid cysts (n = 8), respectively (P<.01). Half of the patients presenting with hyponatremia, including 6 of 10 patients with adenomas and 2 of 3 patients with RCCs, had pituitary apoplexy or cyst rupture. All patients had anterior pituitary gland dysfunction, including 81% with hypoadrenalism and 69% with hypothyroidism. Following surgery, hormonal status was unchanged or improved in 15 patients (median follow-up, 14 months). No patient had tumor/cyst recurrence or recurrent hyponatremia.

CONCLUSION

Severe hyponatremia was a presenting sign in 5.7% of patients with sellar pathology, most frequently in patients with arachnoid cysts, RCCs, and pituitary apoplexy. Patients with new-onset severe hyponatremia and no obvious pharmacologic or systemic cause should undergo pituitary hormonal evaluation and brain imaging. Surgical resection and correction of hormonal deficiencies are associated with resolution of recurrent hyponatremic episodes.