Human vasopressin (arginine-vasopressin, AVP, antidiuretic hormone, ADH) was estimated, after protein precipitation and extraction in ethanol, using a new radioimmunoassay from Immuno Technology Service, Wijchen, Netherlands. Concentrations in human seminal plasma were 1.84 +/- 1.23 (0.6-4.1) pg/ml, estimated in good duplicates in all 20 samples, where 1 pg = 0.410 uIU/ml WHO 1st 77/501. This is
... [Show full abstract] about the same concentration as in blood serum, for which levels up to 8 pg/ml are found by the same kit. In contrast, only trace amounts of vasopressin were found in amniotic fluid at 16-22 weeks of gestation, with zero values in 8 of 19 samples, while another 9 samples showed zero in one duplicate and up to 0.46 pg/ml in the other duplicate, and one sample showed 0.09 pg/ml in good duplicates.