Do lipid profiles of postmenopausal women under oral hormone replacement therapy remain stable or reveal a multiphasic course in time?

Abstract

The object of this study was to compare the effects of oral conjugated estrogen (CEE) alone, CEE plus medroxyprogesterone acetate (MPA) and tibolone on lipid profiles, and investigate whether these effects change in time. Plasma lipid levels were studied for CEE (n = 49), CEE + MPA (n = 50) and tibolone (n = 51). Mean percent changes at certain intervals were compared with their previous intervals for each therapy. Paired t-test was used for statistical analysis. CEE alone had raised high-density lipoprotein (HDL) and triglyceride levels and lowered total cholesterol and low-density lipoprotein (LDL) levels at the end of the 2-year study period. Addition of MPA to the CEE regimen weakened the effect on HDL and triglyceride, augmented the decrease in total cholesterol and did not affect LDL. The tibolone group revealed similar but more prominent effects in total cholesterol and LDL levels. HDL and triglyceride levels were significantly below baseline in the first 6 months, but HDL changes vanished and triglyceride levels remained decreased at the end of 2 years. These data did not support a correlation between lipid levels and the biphasic incidence of cardiac events that were observed in the Heart and Estrogen/Progestin Replacement Study (HERS), but revealed period-dependent cahnges in the tibolone group.