The measurement of 4-androstene-3, 11, 17-trione (11-oxo-androstenedione) by radioimmunoassay in human plasma.

A radioimmunoassay (RIA) method is described for the determination of 4-androstene-3, 11, 17-trione (11-oxo-androstenedione) in human plasma. 4-androstene-3, 11, 17-trione 3-(0-carboxymethyl) oxime-bovine serum albumin conjugate was used to generate highly specific antiserum in rabbits. Cross reactivities of several other steroids with the antiserum were less than 4%. [1,2-3H] 4-androstene-3, 11, 17-trione was synthesized from [1,2-3H] 17 alpha, 21-dihydroxy-4-pregnene-3, 11, 20-trione. The intra- and interassay variation was 7.3% and 9.8%, respectively. The mean serum 4-androstene-3, 11, 17-trione level for healthy young subjects was 2.37 +/- 0.56 nM (X +/- SD) in males and 3.16 +/- 0.43 nM in females at 8 a.m. During the night, there was a marked decrease in serum level, giving at 11 p.m. 0.87 +/- 0.33 and 1.15 +/- 0.52 nM, respectively. During ACTH stimulation tests, 4-androstene-3, 11, 17-trione increased from 1.81 +/- 0.58 to 2.32 +/- 0.69 nM, while in dexamethasone suppression tests a decrease from 3.20 +/- 0.03 nM was seen. In contrast, HCG administration on 3 consecutive days did not influence plasma concentrations of 4-androstene-3, 11, 17-trione.