The effect of monophasic combinations of ethinyl estradiol and norethindrone on gonadotropins, androgens and sex hormone binding globulin: A randomized trial

The effects of different monophasic combinations of ethinyl estradiol and norethindrone on FSH, LH, sex hormone binding globulin, total testosterone, androstenedione, and dehydroepiandrosterone sulfate levels in non-obese, non-hirsute women were compared. Retrospective analysis of frozen serum from a prospective randomized trial in which women received one of three oral contraceptive pills containing ethinyl estradiol 50 μg/norethindrone 1 mg, ethinyl estradiol 35 μg/norethindrone 1 mg or ethinyl estradiol 35 g/norethindrone 0.5 mg for nine cycles was conducted. Blood samples were obtained prior to treatment and during the third, sixth and ninth pill cycles. Ethinyl estradiol 50 μg/norethindrone 1 mg and ethinyl estradiol 35 μg/norethindrone 1 mg suppressed FSH, LH, and total testosterone and increased sex hormone binding globulin to a similar degree. Ethinyl estradiol 35 μg/norethindrone 0.5 mg resulted in less suppression of FSH, LH, and total testosterone, but greater elevation of sex hormone binding globulin. Dehydroepiandrosterone sulfate was suppressed to a similar degree with ethinyl estradiol 35 μg/norethindrone 1 mg and ethinyl estradiol 35 μg/norethindrone 0.5 mg, but ethinyl estradiol 50 μg/norethindrone 1 mg resulted in the least suppression of dehydroepiandrosterone sulfate. Ethinyl estradiol 35 μg/norethindrone 1mg caused greater suppression of androstenedione than did the other two oral contraceptives. Oral contraceptive-induced changes in gonadotropins, androgens, and sex hormone binding globulin can be predicted by considering the relative amounts of estrogen and progestin in the pill. When combined with 1 mg of norethindrone, 50 μg of ethinyl estradiol did not result in greater suppression of FSH, LH, or total testosterone or in greater elevation of sex hormone binding globulin than did 35 μg of ethinyl estradiol.