[Cerebral salt wasting syndrome in a patient with posttraumatic brain injury].

In patients with central nervous system disease, life-threatening hyponatremia can result from either the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) or cerebral salt wasting syndrome (CSWS). Both clinical entities share many similar laboratory and clinical findings, and are characterized by low serum osmolality, inappropriately high urine osmolality, and high urine sodium levels. Despite outward similarities, the pathophysiology and treatment of these two conditions are very different. The former is treated with fluid restriction because of the increased level of free water and its dilutional effect causing hyponatremia, whereas the latter is treated with fluid and sodium resuscitation because of the increased loss of high urinary sodium. We present a 24-year-old man who developed CSWS after traumatic brain injury, showing diagnostic and treatment strategies undertaken in this patient and their impact on the course of CSWS. This case report illustrates the need for clinical awareness of CSWS in patients after head trauma.