Pituitary response to LHRH stimulation in women on oral contraceptives

Isolated follicle-stimulating hormone deficiency in a woman with X chromosomal mosaicism

Primary amenorrhea was observed in a 40-year-old woman with a proportionate female habitus. Serum levels of luteinizing hormone (LH) (71 to 97 mIU/ml) and estradiol (less than 10 pg/ml) were in the postmenopausal range, while follicle-stimulating hormone (FSH) remained at the lower limit of detection (1 to 6 mIU/ml). LH was found to be biologically active in a mouse Leydig cell testosterone production assay. Chromosomal analysis revealed three major cell lines: 5% 45,X; 83% 46,XX; and 3% 47,XXX. The remaining cells showed apparently random aneuploidy and chromosome rearrangements. Intravenous administration of 150 micrograms of gonadotropin-releasing hormone produced a threefold elevation in LH but did not alter FSH levels. Review of ovarian biopsies performed at age 22 revealed a multitude of primordial follicles and one follicle with antrum formation. There was no evidence of recent or past ovulation. An insulin tolerance test evoked normal responses in serum growth hormone, prolactin, and cortisol. This is the first reported case of an isolated deficiency of FSH associated with mosaicism of the X chromosome. This coexistence of functional and genetic aberrations suggests that the differential secretion of LH and FSH may be related to specific independent loci on the X chromosome.

Pituitary response to LHRH stimulation in women on oral contraceptives: a followup dose response study

Gonadotropic response to bolus intravenous injection of LHRH was measured in 36 women. Thirty of them were taking five different oral contraceptive preparations with six women in each category, and the remaining six served as controls. 150 micrograms LHRH was given during cycle days 20-25. Serum samples were obtained prior to the bolus injection and at 20 minute intervals for two hours. Five different oral contraceptive agents were selected to compare different progestins with same type and dose of estrogen, and different type or dose of estrogen with same type and dose of progestins. Significant suppression of LH response to LHRH stimulation ws observed in the agents containing 50 mcg of ethinyl estradiol or mestranol. No such suppression was noted in the product containing only 20 mcg of ethinyl estradiol. In comparing the different type of estrogenic or progestational components, no statistically significant differences in LH response were demonstrated. This finding suggests that it is not the individual component alone, but the combined action of estrogenic and progestational components which determines the potency of an oral contraceptive agent.

Pituitary and ovarian function in women receiving hormonal contraception

A study was performed to further evaluate pituitary-ovarian function in women receiving an oral contraceptive preparation. Basal hormone levels (follicle stimulating hormone, luteinizing hormone, estradiol and prolactin) and gonadotropic response to gonadotropic releasing hormone were studied in 12 healthy, regularly ovulating women in the early follicular and mid-luteal phases of their menstrual cycle (non-treatment control period). These same women were then given NORDETTE (ethinyl estradiol 30 microgram +d-Norgestrel 150 microgram) cyclically for 3 months. In the third month of treatment, the tests were repeated on day 21, i.e. after 21 active pills, and on day 28, i.e. after 21 active and 7 inactive tablets. On active preparation, basal luteinizing hormone, follicle stimulating hormone and estradiol and gonadotropin response to gonadotropin releasing hormone were significantly suppressed. However, by day 28 (after completion of the inactive tablets), basal gonadotropin and estradiol concentrations and the gonadotropic response to gonadotropic releasing hormone were not significantly different to their pretreatment levels. No consistent change in prolactin concentration occurred as a result of oral contraceptive therapy. These results indicate that the 'active' component of even a relatively low-dose pill causes considerable suppression of pituitary-ovarian function but that after 7 days of placebo, pituitary function and basal estradiol secretion have virtually returned to normal.