RADIOIMMUNOASSAY FOR STEROID HORMONES V. RADIOIMMUNOASSAY FOR PLASMA 11-DEOXYCORTISOL
A sensitive and reliable radioimmunoassay for human plasma 11-deoxycortisol has been developed. Antiserum against 11-deoxycortisol was produced in rabbits by immunizing with a 11-deoxycortisol- 3-CMO-BSA conjugate. The antiserum cross-reacted with 17-OH-progesterone, estriol, cortisone, progesterone and estradiolless than 10%. 11-Deoxycortisol in 0.2 ml plasma was extracted with ethylether and separated from cross-reacting steroids by microcolumn chromatography (Sephadex LH-20), with methylene chloride: benzene: methanol (12:7:1, v/v/v) solvent. The intra-assay and the inter-assay precisions were 8.8 and 4.3％, respectively. The mean plasma 11-deoxycortisol concentration at 9:00 a.m. was 1.11 ±0.1 ng/ml (M ± SEM) in twenty healthy controls. Plasma 11-deoxycortisol levels at 4 hours after a single oral administration of Metyrapone (1 g) markedly increased to 113.5 ± 5.6 ng/ml in six healthy men (M ± SEM).