Recurrent Hyponatremia Mimicking Syndrome of Inappropriate Antidiuretic Hormone Secretion: A Case of Partial Empty Sella Syndrome With Isolated Adrenocorticotropic Hormone Deficiency

Hyponatremia is one of the most frequently encountered electrolyte disturbances in clinical practice and can serve as the initial manifestation of various underlying conditions. Severe cases are often associated with neurological dysfunction and an increased risk of mortality. While syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH) remains the most common cause, a thorough diagnostic evaluation is essential, as simple sodium supplementation may lead to recurrent hyponatremia and serious complications. Notably, adrenal insufficiency can closely mimic SIADH, and mismanagement in this context may exacerbate the condition. Hereby, we present the case of a 45-year-old male who experienced recurrent episodes of hyponatremia and was ultimately diagnosed with partial empty sella syndrome. The strong temporal association between corticosteroid administration and symptom resolution, along with low cortisol and adrenocorticotropic hormone (ACTH) levels, suggests that adrenal insufficiency was the primary underlying cause of hyponatremia in this patient.