Hyponatremia can unmask hypopituitarism and secondary adrenal insufficiency due to potent non-osmotic stimulation of vasopressin release under stressful conditions. Patients and methods: In a retrospective study 25 patients (13f/12m, age 58.9±18.6 years) with hyponatremia (119.7±10.5 mmol/l) were identified among 260 in-patients treated for hypopituitarism in our department over a decade. Results: Hyponatremia was recorded in 9.6% of our patients. In 84% it was the key to diagnosis of hypopituitarism. Patients with hyponatremia and non-functioning pituitary macro adenomas (group 1. NFPA n=15) were significantly older (71.47±4.8 years), compared to patients with hyponatremia from other rare causes of hypopituitarism (group 2. n=10; age 40.2±15.3 years, P<0.01): congenital (n=2), Sheehans syndrome (n=2), intracranial aneurysm (n=2), lymphocytic hypophysitis (n=1), traumatic brain injury (n=1), surgery and radiotherapy for astrocytoma (n=1), pituitary metastasis from bronchial carcinoma (n=1). Male preponderance in patients with NFPA (10/15 i.e. 66.7%) was in contrast to female predominance in patients with other causes of hypopituitarism (8/10 i.e. 80%). Hyponatremia was more severe in group 2 compared to group 1 (113.5±10.9 mmol/l vs. 124.3±8.1 mmol/l, P<0.01). Conclusion: Hyponatremia is not uncommon in patients with hypopituitarism, especially at presentation. In older patients, NFPA is the most common pathology, usually leading to gradual onset of hypopituitarisim and non-specific symptoms, while acute hyponatremia can occur with pituitary apoplexy. In younger patients severe acute hyponatremia is more common leading to diagnosis of unrecognized secondary adrenal insufficiency and hypopituitarism from various causes.
20 May 2017 - 23 May 2017