Serum lipids and apolipoproteins in Greek postmenopausal women: Association with estrogen, estrogen-progestin, tibolone and raloxifene therapy

The aim of this study was to assess lipid and apolipoprotein levels in postmenopausal women taking various regimens of replacement therapy or no therapy. Seven hundred forty-eight postmenopausal women followed in the Menopause Clinic of the 2nd Department of Obstetrics and Gynecology, University of Athens, Aretaieion Hospital, were studied in a cross-sectional design. Women were either non-users of replacement therapy (no.=511) or users of one of the following regimens: conjugated equine estrogen 0.625 mg (CEE, no.=34), CEE 0.625 mg plus medroxyprogesterone acetate 5 mg (CEE/MPA, no.=60), 17β-estradiol 2 mg plus norethisterone acetate 1 mg (E2/NETA, no.=44), tibolone 2.5 mg (no.=84), raloxifene HCl 60 mg (no.=51). Total cholesterol (TC), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C), triglycerides (TG), apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB) levels were assessed. Women were grouped according to replacement regimen and mean levels of lipid and apolipoproteins were compared between groups. Women in the raloxifene group were older and longer menopaused. After adjustment for age and duration of menopause, TG levels were significantly lower in the tibolone and E2/NETA groups (75 and 89.9 mg/dl, respectively) compared to non-users. TC was lower in all therapy groups, but the difference acquired significance only in the E2/NETA (207.8 mg/dl), compared to non-users (231.5 mg/dl). LDLC levels were significantly lower in the CEE (133.8 mg/dl), CEE/MPA (130.4 mg/dl) and raloxifene group (129.9 mg/dl) compared to non-users (151.9 mg/dl). There was no difference in HDL-C levels between users and non-users (58.9 mg/dl) except for the tibolone group where HDL-C was significantly lower (48.6 mg/dl). ApoA1 levels were significantly higher in the CEE/MPA group (194.4 mg/dl) and significantly lower in the tibolone group (141.6 mg/dl) compared to non-users (170.4 mg/dl). No difference was detected between groups concerning ApoB levels. In conclusion, tibolone therapy is associated with lower TG levels as well as lower HDL and ApoA1 levels. ERT, continuous combined estrogen-progestin therapy (HRT) and raloxifene are associated with lower LDL-C levels. Among continuous combined HRT users, CEE/MPA is associated with higher ApoA1 levels, while E2/NETA with lower TG levels. Large prospective randomized studies are required to validate these results.