8168 From Salt to the Sella- Discovering Empty Sella Syndrome as a Rare Cause of Severe Hyponatremia

Abstract Disclosure: P. Vemparala: None. S. Challagulla: None. Introduction: Hyponatremia is a common electrolyte disorder with potentially life-threatening consequences. Careful evaluation of hyponatremia can uncover significant underlying conditions. We present an interesting case of a patient who presented with symptoms of severe hyponatremia and a workup led us to the discovery of empty sella syndrome as the etiology. Case Presentation: A 54-year-old male with hypertension presented with 2 days of left-sided headache, blurred vision, generalized weakness, and vomiting. Pertinent medication history revealed the use of thiazide diuretic, bupropion and varenicline. Physical examination was unremarkable. Laboratory data showed severe hyponatremia with a serum sodium of 118 meq/L. Initial improvement with fluids was followed by a decline (106-112 meq/L). CT head without contrast showed a prominent empty sella turcica. Workup revealed urine osmolality and elevated urine sodium. A low AM cortisol level of 1.0 mcg/dl (reference range- AM- 7.0 - 25.0 mcg/dl), and decreased adrenocorticotropic hormone (ACTH) level of 5.2 pg/ml (reference range- 7.2 - 63.3 pg/ml) suggested secondary adrenal insufficiency. All other anterior pituitary hormones were normal. Brain magnetic resonance imaging (MRI) confirmed the diagnosis of partial empty sella. Treatment with hypertonic saline, fluid restriction, and steroids led to symptom resolution. Conclusion: Empty sella syndrome is a rare pituitary condition that can be primary- characterized by herniation of the subarachnoid space within the sella, or secondary- which occurs when the sella is empty due to damage to the pituitary gland by tumor, radiation, etc. It can cause potential hypopituitarism, be asymptomatic, or present with symptoms of raised intracranial pressure. In patients with hypopituitarism, deficiencies of ACTH and TSH are rarer and appear to be more common with a complete empty sella. This case emphasizes the need for a comprehensive hyponatremia workup, awareness of secondary adrenal insufficiency, and recognition of the life-threatening potential of even partial empty sella syndrome when untreated. Presentation: 6/1/2024