Estradiol with or without progesterone and ambulatory blood pressure in postmenopausal women

The purpose of this study was to determine whether transdermal estradiol an d intravaginal progesterone given in doses to mimic the premenopausal state would lower blood pressure (BP) in postmenopausal women. Fifteen healthy p ostmenopausal women were studied in each of 3 conditions: on placebo, after 8 weeks of transdermal estradiol 0.2 mg twice per week, and again 2 weeks after addition of intravaginal progesterone 300 mg/d. Women were studied at each point after 2 days of 100 mmol/d sodium intake. Twenty-four-hour ambu latory BP monitoring was performed, and blood was assayed for estradiol, pr ogesterone, and hormones of the renin-angiotensin-aldosterone system (RAAS) . ANOVA with pairwise comparisons was used for analysis. Urinary sodium exc retion was similar at each time point. Levels of estrogen and progesterone similar to those in premenopausal women were achieved. On estradiol, noctur nal systolic BP (110+/-3 mm Hg), diastolic BP (63+/-2 mm Hg), and mean BP ( 77+/-2 mm Hg) fell significantly (P<0.02) compared with placebo systolic BP (116+/-2 mm Hg), diastolic BP (68+/-2 mm Hg), and mean BP (82+/-2 mm Hg). Daytime BP followed the same trend but was significantly lower only for mea n BP. There was no activation of the RAAS. The addition of progesterone res ulted in no further fall in BP but a significant activation of the RAAS. Th us, contrary to what is often assumed, administration of estradiol with or without progesterone not only did not raise BP but rather substantially low ered BP. This BP-lowering effect may be responsible for the lower incidence of hypertension in premenopausal than in postmenopausal women.