The measurement of androst-4-en-17 beta-ol-3,11-dione (11-oxotestosterone) by radioimmunoassay in human plasma.

A radioimmunoassay was established for the measurement of androst-4-en-17 beta-ol-3,11-dione (11-oxotestosterone). Highly specific antiserum was raised in rabbits using androst-4-en-17 beta-ol-3,11-dione-3-bovine serum albumin conjugate as antigen. Cross reactivity with all steroids measured was less than 4%. [1,2-3H2]androst-4-en-17 beta-ol-3,11-dione was synthesized from [1,2-3H2]pregn-4-ene-17 alpha, 21-diol-3,11,20-trione in a two step reaction with [1,2-3H2]androst-4-ene-3,11,17-trione as intermediate. Purification of plasma androst-4-en-17 beta-ol-3,11-dione was performed by thin-layer chromatography. The intra- and interassay variation was 7.6% and 8.9%, respectively. Furthermore, the radioimmunological procedure was checked against the measurement of androst-4-en-17 beta-ol-3,11-dione in human plasma by gas chromatography/mass spectrometry. Mean plasma levels of androst-4-en-17 beta-ol-3,11-dione at 8 a.m. in healthy young subjects were 2.04 +/- 0.63 nmol/l (means +/- SD) in males and 2.18 +/- 0.89 nmol/l in females. In both groups there was a marked decrease during the night (p less than 0.01), becoming 0.96 +/- 0.33 and 0.96 +/- 0.40 nmol/l, respectively, at 11 p.m. Administration of human chorionic gonadotropin on 3 consecutive days did not influence the plasma concentrations of androst-4-en-17 beta-ol-3,11-dione, whereas both corticotropin (from 2.35 +/- 1.12 to 1.65 +/- 0.76 nmol/l; p less than 0.02) and dexamethasone (from 2.40 +/- 1.75 to 0.40 +/- 0.16 nmol/l; p less than 0.01) caused a significant decrease of androst-4-en-17 beta-ol-3,11-dione.(ABSTRACT TRUNCATED AT 250 WORDS)