Abstract

PIP: Levels of immunoreactive follitropin (FSH), lutropin (LH), estradiol, progesterone, 17-hydroxyprogesterone and 20 alpha-dihydroprogesterone were analyzed in peripheral plasma samples collected daily from 21 normally menstruating women during a pretreatment (control) cycle and during months 2 and 6 of administration of the 300 ug norethisterone (NET) minipill. In the untreated cycles studied, a satisfactory agreement was found between the levels of 20 alpha-dihydroprogesterone and progesterone, whereas the 17-hydroxyprogesterone levels were correlated to those of estradiol. In most of the 42 treatment cycles a satisfactory agreement was found between the assessments based on progesterone levels, and on those of 20 alpha-dihydroprogesterone and 17-hydroxyprogesterone. In the majority of cycles with little or no luteal activity, the profile of 17-hydroxyprogesterone levels appeared to follow that of estradiol. The levels of FSH and LH in 13 subjects in whom the administration of NET suppressed luteal function did not differ from those found in 8 subjects exhibiting normal, ovulatory-like steroid profiles during the minipill administration. Futhermore, in the majority of the treatment cycles in the latter group, the gonadotrophin profiles were bizarre and appeared to be unrelated to the characteristic changes in steroid profiles which sometimes occurred in the virtual absence of any midcycle rise in FSH and LH levels. The 17-hydroxyprogesterone levels of the control cycles were closely related to the nature of the subsequent ovarian reaction to the minipill; in women exhibiting an ovulatory-type steroid response to the subsequent administration of the NET minipill, the pretreatment levels of 17-hydroxyprogesterone were significantly higher than in women in whom this treatment resulted in a complete or incomplete suppression of luteal activity.