HETEROLOGOUS RADIOIMMUNOASSAY FOR ARGININE VASOPRESSIN

Abstract

A sensitive and specific radioimmunoassay for arginine vasopressin (AVP) was developed utilizing the antisera against lysine vasopressin (LVP) in combination with a labeled AVP. The assay employs an acetone extraction procedure and detects as little as 0.8 pg/ml of AVP in human plasma. In normal subjects, the mean (.+-. S.D.) plasma concentration of AVP was 4.9 .+-. 1.2 pg/ml after fluid deprivation and 1.2 .+-. 0.4 pg/ml after water loading. Plasma AVP levels correlated significantly with plasma osmolatities. In 4 patients with diabetes insipidus, plasma AVP concentrations ranged from less than 0.8-1.2 pg/ml, whereas 6 patients with the syndrome of inappropriate antidiuretic hormone secretion showed plasma levels of AVP which correspond to those of the dehydrated state in normal subjects or greater, although plasma osmolalities were low in all cases. The present radioimmunoassay method for AVP provides a useful way of assessing neurohypophyseal function in man.