A Simplified Radioimmunoassay of Serum Pregnenolone

Abstract

A Simplified radioimmunoassay for the measurement of serum pregnenolone is described. Antibodies against pregnenolone were generated in rabbits immunized with pregnenolone 3-bovine serum alubmin conjugate. Since antibodidies having high specificity and sensitivity were obtained, pregnenolone was estimated by the radioimmunoassay after only extraction with hexane without further purification. The sensitivity varied between 0.08 and 0.2ng of pregnenolone. Recovery experiments of pregnenolone added to serum and water confirmed accuracy. Normal serum concentrations of serum pregnenolone determined by this method were; men (1.20±0.20ng/ml); women, follicular phase (1.27±0.15ng/ml) luteal phase (1.42±0.25ng/ml). These mean values were not significantly different from those reported by other workers. The coefficient of variation with in an assay was 8% and it was 16% between assays.