Effect of Continuous Combined Estrogen and Desogestrel Hormone Replacement Therapy on Serum Lipids and Lipoproteins

OBJECTIVE:To determine the effects of continuous combined hormone replacement therapy with desogestrel and 17β-estradiol (E2) on serum lipids and lipoproteins. METHODS:Fifty-seven healthy postmenopausal women of less than 60 years of age were studied prospectively and treated with oral desogestrel 0.15 mg/day and micronized 17β -E2 1 mg/day, both taken continuously. Fasting venous blood samples for serum lipids and lipoproteins were taken before and after 6 and 12 months of treatment. RESULTS:Thirty-two women completed the study. Levels of all serum lipids and lipoproteins fell significantly by 6 months and remained low at 12 months. The mean percentage reduction after 12 months of treatment was 12.8% for high-density lipoprotein (HDL) cholesterol, which largely resulted from a reduction in the HDL2 subtraction, which fell by 25.7%. The mean percentage reduction for both low-density lipoprotein (LDL) cholesterol and triglycerides was 7.7%. The median percentage reduction for lipoprotein (a) was 17.6%. CONCLUSIONS:This combination of hormone replacement therapy had profound effects on serum lipids and lipoproteins. According to current concepts, reductions in total and LDL cholesterol, triglycerides, and lipoprotein (a) may reduce cardiovascular disease risk. The reduction in HDL was unexpected, given the rise in HDL that has been demonstrated when desogestrel is combined with ethinyl estradiol in the contraceptive pill. The lowering of HDL observed in this study is undesirable and may be potentially harmful. Our results indicate that when desogestrel 0.15 mg/day is combined with micronized 17β-E2 1 mg/day in a continuous manner, the effects of the progestogen on HDL predominate and cause a reduction in HDL and the HDL2 subtraction.