[Sensitive radioimmunoassay for plasma arginine vasopressin (author's transl)].

Using an ion exchange resin, a sensitive radioimmunoassay for plasma arginine vasopressin (AVP) was developed. This assay was characterized by the absence of blank values, an excellent recovery rate, great sensitivity (0.1 pg of AVP was significantly detected) and reproducibility. In 8 normal men, plasma AVP after overnight dehydration was 1.57 +/- 0.17 pg/ml and dropped to 0.58 +/- 0.11 pg/ml after 20 ml/kg oral water loading. Significant correlations between plasma AVP levels and plasma or urinary osmolality confirm the validity of this assay. In complete pituitary diabetes insipidus (n = 4) plasma AVP was undetectable whereas it was frankly increased in Schwartz-Bartter syndrome (3 to 33 pg/ml, n = 8).