IMPACT OF HORMONE REPLACEMENT THERAPY ON POSTPRANDIAL LIPOPROTEINS AND LIPOPROTEIN(A) IN NORMOLIPIDEMIC POSTMENOPAUSAL WOMEN

In 43 normolipidemic postmenopausal women we studied fasting and postp randial (oral fat load with 50 g fat per square meter; blood sampling for 5 h) lipoprotein components and lipoprotein(a) levels before and w ith the administration of conjugated equine estrogens opposed by medro gestone (on days 11-21). Data was compared intraindividually; the seco nd testing was performed during the last 5 days of the combined estrog en/progestogen phase of the third cycle. Fasting low-density lipoprote in (LDL) and total cholesterol concentrations decreased significantly; high-density lipoprotein (HDL) cholesterol, including subfractions HD L(2) and HDL(3), was not changed. Fasting triglyceride concentrations increased. All lipoprotein fractions measured showed a postprandial el evation with the exception of chylomicron cholesterol concentrations. There was a significant effect of hormone replacement therapy on the p ostprandial course of total cholesterol (decrease; P < 0.001), VLDL ch olesterol (increase; P = 0.025), and the triglyceride proportion in th e LDL plus HDL fraction (increase; P < 0.001). With hormone replacemen t therapy the postprandial curve of total triglycerides was increased only 1 h after the fat load while chylomicron triglyceride concentrati ons were lowered after 5h. VLDL triglycerides were not influenced. In all patients with lipoprotein(a) levels above 10 mg/dl, this parameter decreased (about 25%). Although increasing fasting triglyceride conce ntrations, hormone replacement therapy does not bring about an exagger ated postprandial increase in triglycerides. Postprandial chylomicron clearance is evidently promoted. Hormone replacement therapy leads to a small increase in triglycerides in the LDL plus HDL fraction by inhi biting hepatic lipase activity. Moreover, the decrease in lipoprotein( a) levels may contribute to the antiatherosclerotic effect.