[Quick radioimmunoassay method for the determination of estrogens]

The aim of this report is to describe a quick method for measuring plasma estrogens by radio immunoassay in one day. Briefly, 1000 cpm of estradiol-3-H were added to 0.1 to 1.5 ml of plasma or serum to calculate losses during the procedure. After ether extraction and without any purification step, aliquots for tracer recoveries and the radioimmunoassay were taken. The antiserum working dilution was 1:100,000. The incubation of the antiserum at 37degreesC with the tritiated and cold estradiol lasts one hour. The free and bound fractions were separated with charcoal/dextran. With this method, 95% of estradiol, 16% of estrone and 6% of estriol are quantified. Other steroids normally present in plasma produce no interference. The minimal detectable level is 10 pg. Pasma and water blanks are indistinguishable of zero (C.V. 1%). Intra-analysis coefficient of variation is 6.1%. Mass recovery of estradiol (5 ng), estrone (5 ng) and estriol (5ng) are 4.75, 0.83 and 0.31 ng, respectively. Tracer recoveries are 92.6%. When plasma levels of estradiol are determined during menstrual cycle, normal and/or pathological pregnancy, by either the method described herein or measured selectively, the results show no significant differences. Finally, practical usefulness of this method is stressed, inasmuch results are obtained in six hours and one person can easily perform 200 samples in one week.