The effect of 2 mg estradiol-17 beta plus 1 mg estriol, sequentially combined with 1 mg norethisteroneacetate, on LH, FSH, estradiol-17 beta, progesterone, testosterone and prolactin after ovariectomy.

The object of the study was to see whether maintenance of serum estradiol levels corresponding to the early and mid-follicular phase can prevent the gonadotrophin increase following ovariectomy. We also wanted to study the effect on LH and FSH of an additional dose of 1 mg dose of 1 mg norethisterone acetate administered for 10 days during each month. In 22 women with normal cycles 1 mg of estradiol benzoate was injected i.m. at the time of ovariectomy. From the first post-operative day onwards they received daily doses of 2 mg estradiol and 1 mg estriol in the form of micronized tablets. From the 41st to the 50th day and again from the 69th to the 78th day the patients received additional daily doses of 1 mg norethisterone acetate. LH, FSH, estradiol-17 beta, (E2) progesterone (P), testosterone (T), and prolactin (PRL) were measured in intervals of 2-17 days. Even though the estradiol mean values remained constant in the range of 65-115 pg throughout the period under observation, the LH mean levels increased continuously from 8 to a maximum of 23.9 mU/ml, and the FSH mean level from a pre-operative value of 6-48.0 mU/ml on the 85th day. On the 7th day after the last administration of norethisterone acetate LH was slightly depressed while FSH continued to rise slightly. Both FSH and LH are negatively correlated with E2 and this inverse correlation becomes even more pronounced the more time has elapsed after surgery. These findings suggest that not only the estrogens inhibit FSH and LH but also other steroids and/or nonsteroidal ovarian inhibiting factors.