Serum estradiol in women ingesting combination oral contraceptive steroids

Abstract

The effect of combination oral steroid contraceptives upon serum estradiol levels was studied in 3 groups of women. Daily blood samples were obtained from 3 women for one control and 2 treatment cycles. Follicle-stimulating hormone, luteinizing hormone, and progesterone were also measured in these samples. In addition, estradiol levels alone were obtained daily and randomly in women who had been receiving long-term hormonal contraceptive therapy. In nearly all women receiving steroid contraceptives, endogenous estradiol levels were low, usually in the 20 to 80 pg. per milliliter range, similar to levels found in the early follicular phase of ovulatory cycles and greater than levels in postmenopausal women. The exogenous estrogen component of the hormonal contraceptives together with this level of endogenous estradiol production should be sufficient to prevent any deleterious effects associated with estrogen deficiency. The finding that estradiol levels remain low in the first cycle of therapy is consistent with previous studies which indicate that one of the mechanisms of action of hormonal contraceptives is a direct effect upon the ovary.