Improved method and its clinical application of a radioimmunoassay of arginine vasopressin in human serum.

A sensitive and specific double-antibody radioimmunoassay for measuring circulating levels of arginine vasopressin in human serum is described. It is possible to detect arginine vasopressin levels of 1 microU/ml serum without extraction procedure. Normal subjects were found to have 5.7 +/- 4.4 microU/ml after a dehydration period of 12 hours. Water loading diminished arginine vasopressin concentrations while dehydration increased it. Application of furosemide over a period of 14 days brought forth constant but not significant decreases. Subjects suffering from psychogenic polydipsia showed normal levels in spite of drinking 8-12 liters of water per day. Patients suffering from liver cirrhosis with ascites showed significantly higher arginine vasopressin levels, approaching normal values, when ascites was under control.