Secondary adrenal insufficiency: an overlooked cause of hyponatremia.

Failure to thrive in an elderly patient is often attributed to depression, especially when a patient does not have any chronic diseases or if there is no apparent medical reason to justify poor appetite, cachexia and generalized weakness. Hyponatremia often occurs in such patients and a thorough evaluation as to its etiology should be sought before committing to a premature diagnosis, which at the time may seem more plausible. We report a patient who presented with depression, weight loss and persistent hyponatremia, evaluation of which revealed the cause to be due to secondary adrenal insufficiency, which when treated, resulted in resolution of the symptom complex. Therefore, in our case report, we elucidate the importance of pursuing further evaluation to rule out adrenal insufficiency as a medical cause of depression, especially in the presence of hyponatremia, which is often overlooked and is generally attributed to dehydration in the setting of failure to thrive or SIADH in patients who are on psychotropic medications.