Medline ® Abstract for Reference 21

The effect of a 2-mo treatment with transdermal estradiol (50 microgram/day) versus placebo on 24 h of blood pressure rhythm was investigated in 18 normotensive healthy postmenopausal women. Whereas daytime blood pressure was not modified, nighttime blood pressure was reduced by estradiol. Estradiol magnified the nocturnal decrement of systolic (14.3 +/- 7.2 vs. 9.8 +/- 6.7 mmHg, P = 0. 0033), diastolic (11.6 +/- 5.0 vs. 7.5 +/- 7.3 mmHg, P = 0.028), and 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 remaining 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 (r2 = 0.38; P = 0.0067). In normotensive postmenopausal women, physiological doses of estradiol amplify the nocturnal decline of blood pressure.