Vasopressin in plasma and CSF of patients with subarachnoid haemorrhage.

Arginine vasopressin was measured in the blood and cerebrospinal fluid (CSF) of 42 patients with subarachnoid haemorrhage. Increased concentrations of vasopressin were present in 10 patients, of whom eight had bled from an anterior communicating artery aneurysm. In three patients high blood vasopressin values were associated with gross hyponatraemia. Five patients were found to have increased CSF vasopressin concentrations in the presence of normal plasma values and in all of these the level of consciousness was severely disturbed. It is suggested that an increased secretion of vasopressin into the blood or CSF may be a contributory factor in the worsening condition of some patients with subarachnoid haemorrhage.