Radioimmunoassay for arginine-vasopressin in cold ethanol extracts of plasma.

A radioimmunoassay for arginine-vasopressin in human plasma with use of a commercially available antibody was developed and evaluated. The hormone was extracted from plasma with cold 98% ethanol, which showed a significantly higher (p less than .001) and more precise recovery than with the acetone-ether procedure (65.3 +/- 3.7% vs 50.8 +/- 6.0%, respectively). The sensitivity was 0.31 pg per tube. Results for normal subjects in different physiological conditions and in patients with diabetes insipidus and inappropriate antidiuretic hormone secretion showed the good reliability of the method.