Serum luteinizing and follicle stimulating hormone levels during sequential and nonsequential contraceptive treatment of eugonadal women.

Abstract

Earlier studies from our laboratory have established the pattern of serum LH and FSH concentrations (measured daily) during the normal menstrual cycle. This manuscript reports the alterations in the daily pattern of both hormones during treatment with sequential and nonsequential contraceptives. The normal menstrual cycle is characterized by: 1) an early follicular phase elevation of serum FSH; 2) a midcycle peak of both serum LH and FSH lasting 24–72 hr; 3) low luteal phase concentrations of both hormones. Fourteen normal women were treated with contraceptive drugs. Six received a nonsequential contraceptive containing the combination of norethynodrel, 2.5 mg, and mestranol, 0.1 mg. All subjects failed to show evidence of either the early FSH elevations or the midcycle LH and FSH peak. Eight women received a sequential contraceptive containing 80 μg mestranol alone for 15 days, followed by 5 days in which 2 mg of chlormadinone acetate was added. The patterns of LH and FSH produced by this sequential contraceptive were bizarre: elevation of serum LH (often multiple peaks) without any rise in serum FSH was noted during the estrogen phase in 6/8 subjects. In 5/8 subjects, additional LH peaks without FSH elevations were observed within 48 hr of the addition of the progestogen. Previously published studies by others have shown that both types of contraceptives prevent ovulation and most studies indicate that exogenous gonadotropin administration reverses this finding. All these data indicate that the nonsequential drugs may have 2 mechanisms of action at the hypothalamic-pituitary level: the suppression of the early FSH elevation and the suppression of the midcycle ovulatory peak. The anti-ovulatory mechanism of action of the sequential drug is more complex but might be explained by the aberrant timing of the LH peak, the ablation of the early rise in FSH, or the suppression of the midcycle FSH peak usually associated with the LH peak. Lastly, these studies demonstrate that an estrogen administered alone to eugonadal women may stimulate LH secretion.