Hormone replacement therapy enhances postprandial lipid metabolism in postmenopausal women

Postmenopausal estrogen therapy reduces cardiovascular morbidity and mortal ity, except in women with advanced coronary disease. This beneficial effect is partly attributed to a reduction of fasting plasma total and low-densit y lipoprotein cholesterol (LDL-C) and an elevation of plasma high-density l ipoprotein cholesterol (HDL-C) concentrations. Since postprandial lipemia s eems to play a role in the pathogenesis of coronary artery disease, we eval uated the effect of hormone replacement therapy (HRT) on postprandial lipop rotein metabolism in 14 normolipemic postmenopausal women. A vitamin A fat- loading test before and after three cycles of treatment with a sequential c ombination of conjugated equine estrogen (CEE) and medroxyprogesterone acet ate (MPA) was used to label chylomicrons and chylomicron remnants with reti nyl palmitate (RP), and RP clearance was assessed over an 8-hour period pos tprandially. Following 3 months of HRT, fasting total cholesterol and LDL-C levels were reduced 9.8% (P = .049) and 16.5% (P = .023), respectively, Pa sting HDL-C levels increased 18.9% (P = .001). Fasting triglycerides (TGs) increased, but not significantly. Postprandial integrated plasma TGs did no t change significantly. The integrated RP levels in whole plasma and chylom icron (Svedberg flotation units [S-f] > 1,000) and nonchylomicron (S-f < 1, 000) fractions were reduced 58% (P = .043), 78% (P = .041), and 75% (P = .0 01), respectively, after hormonal treatment. Enhanced clearance of chylomic rons and chylomicron remnants by HRT may contribute to the protective effec t of estrogens against cardiovascular disease in normolipemic postmenopausa l women. Copyright(C) 1999 by W.B. Saunders Company.