Effects of oral continuous and transdermal cyclic 17-beta estradiol and norethindrone acetate replacement therapy on platelet aggregation in postmenopausal women.

OBJECTIVE: To evaluate the effects of an oral continuous and transdermal cyclic 17-β estradiol and norethindrone acetate combination on platelet aggregation in postmenopausal women. STUDY DESIGN: Fifty postmenopausal women were randomly assigned to receive 17-β estradiol and norethindrone acetate either orally continuously or transdermally cyclically and sequentially. Platelet counts and maximum platelet aggregation rates were measured before and after three months treatment. RESULTS: At three months there were no significant changes in platelet counts or in adenosine diphosphate-induced or epinephrine-induced platelet aggregation rates in either treatment group. CONCLUSION: Hormone replacement treatment with a 17-β estradiol and norethindrone acetate combination either orally continuously or transdermally cyclically and sequentially does not affect platelet aggregation in postmenopausal women.