Cerebral salt wasting versus SIADH: what difference?

The term cerebral salt wasting (CSW) was introduced before the syndrome of inappropriate antidiuretic hormone secretion was described in 1957. Subsequently, CSW virtually vanished, only to reappear a quarter century later in the neurosurgical literature. A valid diagnosis of CSW requires evidence of inappropriate urinary salt losses and reduced "effective arterial blood volume." With no gold standard, the reported measures of volume depletion do not stand scrutiny. We cannot tell the difference between CSW and the syndrome of inappropriate antidiuretic hormone secretion. Furthermore, the distinction does not make a difference; regardless of volume status, hyponatremia complicating intracranial disease should be treated with hypertonic saline.