Ethinyl estradiol and norethindrone radioimmunossay following Sephadex LH-20 column chromatography

Abstract

Combination oral contraceptive pills provide a reliable, reversible and easy to use method of contraception. During the mid-seventies risks of vascular complications were emphasized when pills containing large concentrations of estrogen were used [l], but these risks were diminished when pills containing lower amounts of estrogens were formulated [2], In view of this dose-response effect, complications could still occur with ‘lower dose pills’ if individuals exhibited differences in steroid metabolism. This possibility has, in fact, materialized in several studies demonstrating marked individual variation in plasma ethinyl estradiol concentrations between healthy women ingesting the same oral contraceptive pill [3-51. Acceptance of data from studies such as these, requires knowing that an accurate and reproducible method of steroid hormone measurement had been used. Previous methods of measuring the steroids commonly contained in oral contraceptive pills [ethinyl estradiol (EE) and norethindrone (NE)] have included spectrophotometric or colormetric techniques [6] requiring pretreatment of the plasma sample prior to hormone assay to separate the steroids due to poor specificity of the assay technique. Use of high-performance liquid chromatography has also been described for this purpose [6].