Endometrial estradiol-17 beta-dehydrogenase activity in women wearing Cu-IUD

In order to determine whether inhibition of the endometrial estradiol-17 beta-dehydrogenase activity by Cu++ could be one of the factors accounting for the enhanced contraceptive efficacy of copper intrauterine devices (Cu-IUD), the activity of the enzyme was measured in endometrial biopsies from women wearing this device. The levels of enzymatic activity found in these specimens were within the range of controls (women without IUD), e.g. 0.1--0.8 and 7--27 nmol E1 formed/mg protein/h in the follicular and luteal phases of the menstrual cycle, respectively. It is concluded that Cu-IUD does not modify significantly either the activity of endometrial-17 beta-dehydrogenase, an enzyme known to regulate the tissular concentration of estradiol, or its response to the inductive effect of progesterone.