Severe recurrent hyponatremia in a 72-year-old patient with undiagnosed partially empty Sella syndrome-a case report.

Hyponatremia is one of the most common electrolyte abnormalities encountered in medical practice and is caused by multiple conditions. SIADH is the most common cause of hyponatremia, however, careful workup must be performed on all patients as mere supplementation may cause recurrent hyponatremia and serious side effects. Adrenal insufficiency is a principal culprit that mimics the clinical picture of SIADH and tends to worsen when treated in the line of SIADH. In addition, individuals may have various comorbidities, such as hypothyroidism in our case, which can also cause hyponatremia, making it difficult to determine precise etiology. We present a case of a 72-year-old man with recurrent hyponatremia, who was subsequently diagnosed as partially empty sella syndrome. Given the temporal relationship between the use of corticosteroids and the improvement of his symptoms, low cortisol and ACTH levels, adrenal insufficiency was most likely the cause of the hyponatremia in our patient.