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pubmed:otherAbstract |
PIP: The effects of oral contraceptives and estrogen replacement drugs on blood lipids that affect cardiovascular disease (atherogenic effects) are reviewed by comparing their androgenicity and progestin potency. Although early oral contraceptives with high doses of estrogen were indicted for increasing risk of thromboembolic disorders and heart attacks, today's pills low in estrogen still bear the same risk for cardiovascular events. A brief explanation of the lipoproteins is presented, emphasizing the importance of High Density Lipoprotein (HDL) in protecting against heart disease and stroke. Menstruating women have naturally high HDL. The estrogen in oral contraceptives and postmenopausal estrogen replacements increases HDL as much as 30%, while decreasing LDL, the component carrying most of the cholesterol. It seems that the progestin in oral contraceptives will lower HDL, and studies show that this action is related to androgenicity and dose of the progestin. Progestins such as levonorgestrel and norgestrel are more androgenic, while norethynodrel, ethynodiol diacetate and norethindrone are less so. When used in combination with estrogens, progestins are less androgenic, but when used alone, the androgenic and atherogenic effects dominate. The lower the estrogen dose in the combination, say around 20-35 mcg ethinyl estradiol, the more atherogenic the progestin. These actions are confirmed theoretically by measurements of sex hormone binding globulin, a blood protein that reflects estrogen activity, as well as by epidemiologic studies in Sweden and Great Britain, where rates of heart attack and stroke in pill users remain as high as they were when pills contained high doses of estrogen.
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