The measurement of 11 beta, 17 beta-dihydroxy-4-androsten-3-one (11 beta-hydroxytestosterone) by radioimmunoassay in human plasma.

A radioimmunoassay (RIA) is described for the measurement of 11 beta,17 beta-dihydroxy-4-androsten-3-one (11 beta-hydroxytestosterone) in human plasma. The reliability criteria of the new RIA were similar to those of other steroid hormone radioimmunoassays. The mean plasma 11 beta,17 beta-dihydroxy-4-androsten-3-one level for healthy young subjects was 1.31 +/- 0.32 nmol/l (means +/- SD) in males and 1.19 +/- 0.35 nmol/l in females at 8 a.m.; during the night, there was a marked decrease, and at 11 p.m. the recorded values were 0.41 +/- 0.15 nmol/l and 0.46 +/- 0.14 nmol/l, respectively. During the corticotropin stimulation test, 11 beta,17 beta-dihydroxy-4-androsten-3-one increased from 1.03 +/- 0.33 nmol/l to 1.31 +/- 0.41 nmol/l, while in dexamethasone suppression tests a decrease from 2.04 +/- 0.82 nmol/l to 0.25 +/- 0.05 nmol/l was seen. In contrast, chorionic gonadotropin administration on 3 consecutive days did not influence plasma concentrations of 11 beta,17 beta-dihydroxy-4-androsten-3-one.