Cerbral salt wasting syndrome versus SIADH

In the context of cerebral diseases the two main mechanisms responsible for non iatrogenic causes of hyponatremia are cerebral salt wasting syndrome (CSW) and inappropriate secretion of antidiuretic hormone (SIADH). Distinction between these two syndromes is difficult and is based on the assessment of the patient's volume status. In case of CSW, the volume status is low and the treatment is fluid and sodium replacement. In case of SIADH the volume status is normal or slightly expanded and the treatment is fluid restriction. To avoid centropontine myelinolysis, the speed of correction should not exceed 8 to 10 mmol/L over a 24-hour period. This article will describe practical tools to differentiate CSW from SIADH and therapeutic strategies useful in daily clinical practice.