[A specific radioimmunologi determination of plasma estradiol without chromatography during the cycle and in pregnancy and determination of the free non-protein-bound fraction using dialysis].

The plasma concentrations of estradiol were measured by radioimmunoassay without chromatography. The antibody against estradiol was produced in rabbits immunized with 17beta-estra-diol-6-(0-carboxymethyloxime): bovine-serum-albumin. The lower limit of quantitation is 2.6 pg estradiol. A coefficient of variation of 5.9% was ascertained. The recovery of this method is 93% in the range of 89.8 to 95.2%. The concentrations of estradiol during the menstrual cycle are from 30 pg/ml to 300 pg/ml. Estradiol levels during the anovulatory cycle were found below 70 pg/ml. Similar values (2.0 to 2.5%) of percent of unbound estradiol in normal and anovulatory cycle were calculated. The concentrations of estradiol increase in pregnancy on an average of 16 ng/ml. The percentage of free estradiol decreases (up to the 24 weeks of pregnancy) from 2.3% to 1.2%.