Comparison of the effects of contraceptive steroid formulations containing two doses of estrogen on pituitary function

Abstract

A pituitary stimulation test with gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) was undertaken to determine (1) whether pituitary responses to GnRH vary in individual women taking oral contraceptive steroids over time, (2) whether a less suppressive pituitary gonadotropin effect is produced by formulations containing less than 50 microgram of estrogen, and (3) to obtain more information concerning prolactin secretion in users of oral contraceptive steroids. The same subjects who had had a suppressed luteinizing hormone (LH) and follicle-stimulating hormone (FSH) response 6 to 9 months previously also had a suppressed response, indicating that this effect persists over time. Contraceptive formulations containing less than 50 microgram of estrogen have a lesser suppressive effect on LH release than do formulations containing 50 microgram of estrogen or more. The basal prolactin (PRL) response as well as the maximal PRL response to TRH were found to be significantly greater in subjects using oral contraceptives than in the control subjects. However, no difference in PRL response was found between the subjects using low or high doses of estrogen fomulations.

PIP: A comparison of the effects of contraceptive steroid formulations containing 2 doses of estrogen on pituitary function is reported. The gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) stimulation tests were carried out with 11 control women, 23-38 years of age, and 39 women receiving various oral contraceptive (OC) formulations. The responses to GnRH stimulation were similar in the same subjects who had been stimulated 6-9 months previously, indicating that the effect persists over time. OCs containing less than 50 mcg of estrogen showed a lesser suppressive effect on luteinizing hormone (LH) release than did OCs containing 50 mcg or more of estrogen (p .001). Peak serum follicle stimulating responses were significantly lower (p .01) than those of controls, but there was no marked difference between the 2 groups of OC users. Basal prolactin (PRL) response as well as the maximal PRL response to TRH were significantly greater (p .025 and p .05), respectively) in subjects using OCs than in the control subjects. It is concluded that OCs have a suppressive effect on pituitary gonadotropin release in most users, which is independent of the dose of estrogen.