Progesterone does not influence vascular function in postmenopausal women

Background The protective functions of oestrogen therapy alone on cardiovascular risk parameters are well established; however, the action of progesterone on vascular parameters in an oestrogen-deprived environment is less clear. Objectives To examine the effects of progesterone alone on vascular function and hormone levels in postmenopausal women. Design In a randomized, double-blind, cross-over design study, 20 healthy postmenopausal women were tested before and after 6 weeks of treatment with micronized progesterone (100 mg/daily) and matching placebo. Methods Tests included measurement of sex hormones and gonadatropin levels, lipids and measures of surrogate markers of vascular function including, blood pressure, flow-mediated dilation of the brachial artery, systemic arterial compliance and cutaneous vascular reactivity. Results The mean (+/- SEM) age of subjects was 56.4 +/- 2.7 years and the average body mass index at the baseline visit was 27.1 +/- 1.0 kg/m(2). Progesterone levels increased as a result of progesterone treatment (0.9 +/- 0.2 to 9.5 +/- 2.3 nmol/l, P = 0.001), whereas follicle-stimulating hormone levels decreased (75.1 +/- 11.4 to 67.6 +/- 10.0, P = 0.001). Systemic arterial compliance, flow mediated dilation, cutaneous vascular reactivity, blood pressure, body mass index, plasma levels of cholesterol, lipids and oestrogen were unchanged. Conclusions We conclude that progesterone given without oestrogen does not adversely affect vascular function in postmenopausal women.