QUANTITATIVE AND QUALITATIVE CHANGES IN LIPIDS, LIPOPROTEINS, APOLIPOPROTEIN-A-I, AND SEX HORMONE-BINDING GLOBULIN DUE TO 2 DOSES OF CONJUGATED EQUINE ESTROGEN WITH AND WITHOUT A PROGESTIN

Objective: To determine whether the quantitative and qualitative effec ts on lipoproteins differ between two doses of conjugated equine estro gen before and after progestin administration. Methods: We randomized 103 postmenopausal women into a control group and into two groups rece iving either 0.625 mg or 1.25 mg of conjugated equine estrogen for 4 m onths and then the same estrogen dose plus cyclic medroxg progesterone acetate for 8 months. Results: Both estrogen doses similarly lowered (P < .01) low-density lipoprotein (LDL) cholesterol and raised (P < .0 1) high-density lipoprotein (HDL) cholesterol, apolipoprotein A-I, tri glyceride levels of all lipoproteins, and sex hormone-binding globulin capacity. Cyclic addition of the progestin reduced HDL cholesterol (P < .01) and apolipoprotein A-I (P < .05), but not LDL cholesterol in e ither estrogen group. A greater lowering of HDL cholesterol (P < .05) in response to the progestin was seen with the 0.625-mg dose of estrog en. Estrogen-induced triglyceride enrichment of HDL and LDL was not re versed by the progestin. Conclusion: The only significant quantitative difference in lipoprotein levels between the doses of conjugated equi ne estrogen before or after administration of medroxyprogesterone acet ate was a greater decline in HDL cholesterol levels with the lower dos e after 4 months of the progestin. This difference was not sustained o ver time. There were no differences between doses in the estrogen-indu ced triglyceride enrichment of lipoproteins, and these qualitative cha nges were not affected by the progestin.