Physiological doses of estradiol decrease nocturnal blood pressure in normotensive postmenopausal women

The effect of a 2-mo treatment with transdermal estradiol (50 mu g/day) ver sus placebo on 24 h of blood pressure rhythm was investigated in 18 normote nsive healthy postmenopausal women. Whereas daytime blood pressure was not modified, nighttime blood pressure was reduced by estradiol. Estradiol magn ified the nocturnal decrement of systolic (14.3 +/- 7.2 vs. 9.8 +/- 6.7 mmH g, P = 0.0033), diastolic (11.6 +/- 5.0 vs. 7.5 +/- 7.3 mmHg, P = 0.028), a nd mean (10.8 +/- 5.6 vs. 7.2 +/- 4.5 mmHg, P = 0.011) blood pressure. As a consequence, the 24-h rhythm of mean blood pressure was restored in 50% of the subjects (P = 0.045) in whom it was absent and was amplified in the re maining 50% of the subjects. Body mass index was an independent determinant of blood pressure values being directly related to the amplitude of the 24 -h mean blood pressure rhythm (r(2) = 0.38; P = 0.0067). In normotensive po stmenopausal women, physiological doses of estradiol amplify the nocturnal decline of blood pressure.