EFFECTS OF HORMONE REPLACEMENT THERAPY ON LIPOPROTEIN(A) AND LIPIDS IN POSTMENOPAUSAL WOMEN

High concentrations of lipoprotein(a) [Lp(a)], an independent risk fac tor for atherosclerosis, cannot be managed by the usual lipid-lowering agents. It has been suggested that Lp(a) levels are related to female sex hormones. Estrogen replacement therapy makes the lipid profiles f avorable for delaying atherosclerosis in postmenopausal women. The eff ects of the combination therapy of estrogen and progesterone on lipids are controversial. This study was designed to evaluate the effect of female sex hormones on the concentration of Lp(a) and to clarify the i nfluence of progesterone on the effect of estrogen in postmenopausal w omen. Postmenopausal women (n=184) were divided into four groups: cont rol; 0.625 mg conjugated equine estrogen (CEE) plus 10 mg medroxyproge sterone acetate (MPA); 0.625 mg CEE plus 5 mg MPA; and 0.625 mg CEE on ly. Medication for 2 months lowered the concentrations of Lp(a) by 20% in all treated groups. The decrease was more pronounced in subjects w ith a relatively higher basal Lp(a) concentration. Estrogen replacemen t therapy raised the concentration of high-density lipoprotein cholest erol and decreased low-density lipoprotein cholesterol without changin g total cholesterol. The combination therapy of estrogen and progester one abolished the effect of estrogen on high-density lipoprotein chole sterol. Hormone replacement therapy lowered Lp(a) levels in postmenopa usal women. The effect was prominent in subjects with high basal Lp(a) levels. This decrease may be one of the mechanisms of the cardioprote ctive effects of estrogen. The cardioprotective effect of estrogen can not be applied to the combination therapy due to the adverse effect of progesterone on high-density lipoprotein cholesterol.