Determination of serum 17 alpha-hydroxyprogesterone by liquid chromatography

17 alpha-Hydroxyprogesterone, cortisol, and 11-deoxycortisol were extracted with methylene chloride, separated by liquid chromatography, identified by their retention times, and quantitated by monitoring the absorbance at 254 nm. The method is specific and sensitive to as little as 2.5 ng of 17 alpha-hydroxyprogesterone. Mean analytical recovery of added 17 alpha-hydroxyprogesterone was 99% (SD 11%) and the CV for the same or different assays ranged from 3.5 to 9.4%. 6 beta-Hydroxyprogesterone was used as the internal standard. Concentrations of 17 alpha-hydroxyprogesterone in serum of normal men and women were less than 2.5 micrograms/L, but women in the luteal phase of the menstrual cycle had higher values. Mean 17 alpha-hydroxyprogesterone content in serum from mixed cord blood of normal newborns was 28.1 (SD 13.8) micrograms/L. Results by this method correlated well (r = 0.97) with results by radioimmunoassay, but were somewhat higher.