# Recurrent Hyponatremia With Central Endocrine Dysfunction: A Diagnostic Challenge

## TL;DR

A man with chronic hyponatremia and endocrine issues was found to have a pituitary mass, which was successfully treated, resolving his symptoms.

## Contribution

This case demonstrates that pituitary masses can mimic SIADH and highlights the importance of structural evaluation in such patients.

## Key findings

- A suprasellar cystic mass was identified as the cause of hyponatremia and endocrine dysfunction.
- Transsphenoidal cyst drainage resolved hyponatremia and normalized pituitary function.
- Timely intervention reversed endocrine abnormalities and sodium levels.

## Abstract

A 55-year-old man with a history of chronic hyponatremia presented with recurrent nausea, vomiting, and severe hyponatremia. Initial evaluation revealed features consistent with the syndrome of inappropriate antidiuretic hormone secretion (SIADH), including hypotonic hyponatremia with inappropriately concentrated urine. Further workup demonstrated concurrent central hypothyroidism and hypogonadotropic hypogonadism, prompting neuroimaging. MRI identified a 1.7 cm suprasellar cystic mass compressing the pituitary infundibulum. The patient underwent transsphenoidal cyst drainage, resulting in the resolution of hyponatremia and normalization of pituitary function. This case highlights the importance of evaluating structural pituitary pathology in patients with hyponatremia and multiple endocrine abnormalities, demonstrating how compressive lesions can mimic idiopathic SIADH. The rapid postoperative normalization of sodium and hormonal axes underscores the reversibility of such deficits with timely intervention.