RADIOIMMUNOASSAY FOR STEROID HORMONES Ⅳ. RADIOIMMUNOASSAY FOR PLASMA PREGNENOLONE
A convenient and reliable radioimmunoassay for plasma pregnenolone has been developed. Anti-pregnenolone serum was obtained by immunizing rabbits with a pregnenolone-3-hemisuccinate-BSA conjugate. A useful range in the standard curve was from 10 pg to 500 pg. Pregnenolone in 0.1 ml plasma was extracted with ether and was separated from cross-reacting steroids by microcolumn chromatography. Plasma concentrations of pregnenolone at 9 a.m. were: men, 0.91±0.17 ng/ml; women, 1.06±0.37 ng/ml.
