[Radioimmune determination of steroids--comparison of 2 variants of the methods]

Various conditions of radioimmunoassay (RIA) technique for estimation of 19-nortestosterone and methandrostenolone were studied. Dilution of antiserum, required for 50% binding of the labelled steroids, depended primarily on the RIA procedure used. When 19-nortestosterone was estimated by means of these two RIA procedures, the final dilution of antiserum was equal to 1:24,000 and 1:475,000, respectively. Characteristics of standard curves, sensitivity and accuracy were similar in these RIA procedures, but the rate of cross-reactions between antiserum and the steroids was different. Both RIA procedures indicated similar values of methandroctenolone and 19-nortestosterone content excreted with urine after oral administration of the steroids.