Triphasic pills: variability of endocrine parameters and of sex steroid-binding globulins.

A hundred and twenty healthy women who did not desire pregnancy were selected to check the effects of triphasic oral contraceptives on endocrine parameters and on plasma levels of steroid-binding proteins. Three groups of 40 women each were treated with 3 different pills containing different doses of ethynilestradiol in combination with noretistherone or levonorgestrel or gestodene, for a 6-month period. Serum concentrations of pituitary, ovarian and adrenal hormones, sex-hormone binding globulin and corticosteroid binding globulin were measured, basally and after the 6th cycle. Triiodothyronine and thyroxine were also tested. After 6 cycles the three oral contraceptives determined the inhibition of gonadotropins, ovarian steroids and Dehydroepiandrosterone Sulphate as well as an increase in Cortisol, triiodothyronine, thyroxine, sex hormone binding globulin and corticosteroid binding globulin. Prolactin levels did not vary. In the groups that receive the pills containing noretistherone, levonorgestrel and gestodene, sex hormone binding globulin increased by 138-136 and 156 per cent respectively, while corticosteroid binding globulin increased by 89-75 and 82 per cent respectively. The higher increase in sex hormone binding globulin, caused by gestodene-containing pill, testifies to the selectivity of this progestogen towards a lower androgenicity than norethisterone and levonorgestrel.