[Severe hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone].

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a common and multifactorial cause of hyponatremia that is often overlooked. The common pathophysiological mechanism is the increased production and/or action of antidiuretic hormone within the kidney, resulting in hypotonic hyponatremia. Inadequate correction of hyponatremia may have fatal neurological consequences leading to central pontine myelinolysis. We report the case of a patient with a history of recent head trauma, who came to our observation for acute-onset mental confusion secondary to severe hyponatremia due to SIADH of combined etiology.