Differences in low density lipoprotein subfractions and apolipoproteins in premenopausal and postmenopausal women.

Postmenopausal or oophorectomized women are at higher risk for the development of coronary artery disease than are premenopausal women. These differences in risk may be due to alternations in plasma lipoproteins modulated by hormonal changes. Plasma cholesterol, triglyceride, lipoprotein cholesterol, and apolipoprotein A-I and B (apoB) concentrations, as well as low density lipoprotein (LDL) particle size (LDL 1-7), as assessed by 2-16% polyacrylamide-agarose gradient gel electrophoresis, were determined in 87 premenopausal and 43 postmenopausal women. All were participants in the Framingham Offspring Study, were gynecologically normal, and were not taking any hormones. The postmenopausal women had significantly (P less than 0.05) higher plasma LDL cholesterol concentrations than did the premenopausal women. Plasma triglyceride, total cholesterol, very low density lipoprotein cholesterol, and apoB levels were higher, and apoA-I and high density lipoprotein cholesterol were lower in the postmenopausal group, but these differences were not significant at P less than 0.05. The postmenopausal women were likely to have small LDL particles compared to premenopausal women. Controlling for age and body mass index effects significantly reduced the differences in total cholesterol, LDL cholesterol, apoB, and LDL particle size and broadened the differences in apoA-I and high density lipoprotein cholesterol. These data indicate that menopause is positively correlated with LDL cholesterol (P less than 0.05) and decreased LDL particle size (P less than 0.05) after adjusting for significant covariates.