Cerebral salt-wasting syndrome - We need better proof of its existence

It is widely believed that the cerebral salt-wasting syndrome (CSWS) exists as an entity distinct from the syndrome of inappropriate ADH secretion, an d that it is characterized by evidence of severe renal salt wasting that re sults in volume depletion and hyponatremia. Proof of the existence of CSWS as an entity requires documentation of renal salt wasting and volume deplet ion. The present review has been undertaken to examine the evidence that th e CSWS is a separate entity. In this effort, we have discussed various meth ods of documentation of volume depletion, and then reviewed reported cases of CSWS to determine whether volume depletion and renal salt wasting have b een clearly demonstrated. Our review has led us to conclude that not one ca se of purported CSWS has demonstrated clear evidence of volume depletion an d renal salt wasting. If renal salt wasting had been proven in these cases, we would conclude that the likely site of renal salt transport was the pro ximal tubule, The proximal site of salt transport defect has been suggested by the absence of hyperreninemia and hypokalemia, which would be a disting uishing feature of Bartter's syndrome and Gitelman's syndrome.