Changes in the lipoprotein profile in postmenopausal women receiving hormone replacement therapy: Effects of natural and synthetic progesterone

OBJECTIVE: To compare the effects of medroxyprogesterone acetate and micronized progesterone on the lipid profile of postmenopausal women receiving conjugated equine estrogen. STUDY DESIGN: A prospective, clinical study of the changes in lipoprotein profile evaluated in 123 postmenopausal women receiving conjugated estrogen alone (group I), conjugated estrogen combined with medroxyprogesterone acetate (group II) or micronized progesterone (group III) before treatment and six months after. RESULTS: Group I had significantly increased high-density lipoprotein cholesterol (HDL-C) levels (14.4%) after six months as well as decreased low-density lipoprotein cholesterol (LDL-C) concentrations (-6.61%), LDL/HDL and total cholesterol/HDL-C ratios (P < .05). In groups II and III, HDL-C concentrations increased 4.58% and 5.44%, respectively, after six months. LDL-C levels were markedly decreased in group II (8.98%). There was no significant reduction in LDL-C levels in group III. Total cholesterol levels were significantly decreased only in group II (-4.93%). Triglyceride levels were increased with statistical significance only in group III (21.2%, P<.05). LDL/HDL and total cholesterol/HDL-C ratios were significantly decreased in group II, and this effect was more pronounced in group I. There was no change in the ratios in group III. CONCLUSION: Conjugated estrogen replacement therapy had a persistent cardio-protective effect in postmenopausal women, based on the positive effect on lipoprotein metabolism. Both natural and synthetic progesterones blunt the beneficial effects of estrogen on the lipoprotein profile, and micronized progesterone is not superior to medroxyprogesterone acetate.