Influence of bilateral oophorectomy upon lipid metabolism

Objectives: Reduction in serum level of estrogen has been thought to result in hyperlipidemia which triggers atherosclerosis, and even to lead to cardiovascular diseases, in postmenopausal women. The present study was designed to investigate the influence of bilateral oophorectomy (OPX), which induces as much reduction in serum estrogen level as menopause, upon lipid metabolism, especially the serum levels of total cholesterol. Methods: In 31 OPX subjects and 31 age- and body size-matched premenopausal controls, the serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein (VLDL-C), apoprotein-A1 (Apo-A1), apoprotein-B (Apo-B), lipoprotein lipase (LPL) and lipoprotein-a [LP(a)] were measured as indices of lipid metabolism and the index of arteriosclerosis was calculated. Results: TC level was significantly higher in the OPX group than in the premenopausal control group, being 8995±244 (mean±S.E.) mmol/l and 7757±228 mmol/l, respectively. LDL-C and Apo-B levels and the index of arteriosclerosis were all significantly higher in the OPX group than in the premenopausal control groups. However, there were no significant intergroup differences with regard to HDL-C, Apo-A1, LPL and LP(a). Conclusions: The above results demonstrated that, in spite of no reduction in HDL-C, the blood levels of Apo-B, LDL-C and TC change due to OPX. These changes suggest OPX induces cardiovascular diseases and, therefore, follow-up of the changes in lipid metabolism is required, paying special attention to Apo-B and LDL-C.