Comparison of the effects of conjugated estrogen treatment on blood lipid and lipoprotein levels when initiated in the first or fifth postmenopausal year.

Although estrogen replacement therapy (ERT) is known to be protective against the development of cardiovascular disease in patients with surgical menopause, the effects of ERT on blood lipids when started late after the operation is not yet clear. In this prospective study, blood lipid and lipoprotein levels were measured within a 2 year period, in Group I (n = 28 patients) and in Group II (n = 21 patients), who had total abdominal hysterectomy and bilateral salphingo-oophorectomy 10-16 or 55-65 months ago, respectively. Each patient received 0.625 mg conjugated equine estrogen once daily. Blood levels of total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL), high density lipoprotein (HDL) and very low density lipoprotein (VLDL) were measured at the beginning of the study as well as 12 and 24 months after ERT, was commenced. When the levels obtained after 12 and 24 months of ERT were compared to the baseline levels, LDL levels were decreased, whereas HDL levels were increased in Group I (p < 0.05); however, only the TC levels were significantly lower in Group II (p < 0.05). In conclusion, our results show that ERT is more effective on blood lipid changes when initiated within one year of oophorectomy compared with ERT initiated 5 years after the menopause.