Radioimmunoassay method for six steroids in human plasma

A rodioimmunoassay method has been developed for the simultaneous determination of progesterone, 3β-hydroxy-5-pregnen-20-one, 3β-hydroxy-5-androsten-17-one, testosterone,estrone and estradiol in 2 ml plasma samples.The first three steroids are isolated on a celite:propylene glycol column (1:1 w/v),the latter three steroids on a celite:ethylene glycol column (2:1 w/v). Steroids obtained from individual chromatographic fractions are incubated for 40 min.with the appropriate antisera and labelled steroids and the bound and free fractions are separated by charcoal. Precision and accuracy studies have shown that the assays of all steroids are reproducible and accurate. Specificity studies carried out with 57 steroids,in conjunction with the accuracy experiments, indicate that a very high degree of specificity has been achieved. One possible exception may be the assay of 3β-hydroxy-5-pregnen-20-one. In this assay 3β-hydroxy-5α-pregnan-20-one,if present in plasma in appreciable amounts, would lead to an overestimation.