Cerebral Salt Wasting Syndrome: Diagnosis By Urine Sodium Excretion

Abstract Background Cerebral salt wasting syndrome (CSWS) was initially described over 60 years ago in hyponatremic patients with a cerebral lesion. However, the diagnostic criteria for CSWS have not been fully established. Thus, when hyponatremia is observed in patients with CSWS, they may be misdiagnosed as having the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Thus, it is critical to differentiate between these two conditions because their treatments are diametrically opposed. Methods We carried out a retrospective study of 45 patients with CSWS and compared them to 60 normonatremic control patients, and 28 patients with SIADH. All patients had their 24 hour urine volumes and Na excretion measured. Results Patients with either CSWS or SIADH had an elevated 24 hour urine osmolality (above 350 mOsm/kg). In patients with CSWS, urinary Na excretion was 394 ± 369 mmol/24 hour, and urinary volume was 2603 ± 996 ml/24 hour; both values significantly greater than in controls (p