Effects of progestin-estrogen combination and progestational contraceptives on pituitary gonadotropins, gonadal steroids and sex hormone-binding globulin.
The effects of three kinds of hormonal contraceptives on the levels of follicle-stimulating (FSH), luteinizing hormone (LH), estradiol, progesterone, testosterone, and sex hormone-binding globulins (SHBG) in three groups of normally menstruating women were analyzed. During the administration of a very low-dose combination of 150 micrograms of D-norgestrel and 30 micrograms of ethinylestradiol, a progressive suppression of LH, FSH, estradiol, and (to a lesser extent) testosterone levels was observed while progesterone stayed at levels found during the early follicular phase. SHBG levels in these subjects were within the normal range for women. Oral treatment with 0.5 mg of lynestrenol and the intramuscular administration of 200 mg of norethindrone enanthate produced a suppression of LH but not FSH in all cases. Estradiol levels showed peaks in the three women treated with lynestrenol and in half of those treated with norethindrone enanthate, suggesting follicular activity caused by the unsuppressed FSH stimulus; the subsequent elevation of progesterone in two subjects suggested some luteinization, although there was no evidence of an ovulatory surge of gonadotropins. The SHBG in four subjects treated with norethindrone enanthate fell within our normal range for men, and the mean serum testosterone levels fell 40% below the normal basal levels in these cases.