Hyponatremia in neurological patients: cerebral salt wasting versus inappropriate antidiuretic hormone secretion.

Abstract

To assess whether hyponatremia in acute neurological patients is associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or with the cerebral salt-wasting syndrome (CSWS). Clinical, controlled, prospective study. Department of intensive care of a tertiary care academic hospital. Forty acute neurological patients with hyponatremia suggesting SIADH or CSWS (20) or with normonatremia (20). None. Measurement of clinical and biological variables. Measurement of blood, plasma, and red blood cell volumes to discriminate SIADH and CSWS. Renal, adrenal and thyroid functions were normal in all patients. Average blood, plasma, and red blood cell volumes were 54, 37 and 17ml/kg in control patients and 54, 37 and 18ml/kg in hyponatremic patients, respectively. The adequate blood volumes in hyponatremic patients confirm the diagnosis of SIADH and do not support the concept of CSWS.