Neurosurgical hyponatremia: the role of inappropriate antidiuresis

Abstract

✓ Of 80 consecutive neurosurgical patients, 23 exhibited inappropriate secretion of the antidiuretic hormone (ISADH); 11 of these patients required marked fluid restriction. Sodium concentration in the urine characteristically increased as serum values decreased. Only by following the urine sodium concentrations could the differential diagnosis of nutritional hyponatremia and ISADH be made. The role of ISADH in cerebral edema is stressed. The treatment recommended for ISADH is marked fluid restriction, whereas in nutritional hyponatremia, saline replacement is indicated.