Purpose: To study the influence of combined hormone replacement therapy on levels of serum lipids, lipoproteins, and apolipoproteins.
Patients and methods: One hundred thirty-nine healthy early postmenopausal women selected by means of a questionnaire, a medical examination, and a laboratory screening procedure to be a representative sample of postmenopausal Danish women aged 45 to 55 years old were randomized to four treatment and two placebo groups. The four groups receiving hormone replacement therapy were given 2 mg estradiol valerate equivalents (E), either sequentially combined with 75 micrograms levonorgestrel (E/LNG), 10 mg medroxyprogesterone acetate (E/MPA), or 150 micrograms desogestrel (E/DG), or continuously combined with 1 mg cyproterone acetate (E/CPA). Serum lipids, lipoproteins, and apolipoproteins were measured before institution of hormone replacement therapy and at nine well-defined times during the following 84 days. Total response and cyclical variations were calculated.
Results: All active treatment regimens reduced serum low-density lipoprotein cholesterol (LDL-C) significantly: E/CPA, 6% (95% confidence limits 0.3% to 11.3%); E/LNG, 10.9% (4.9% to 16.6%); E/MPA, 14.4% (7.4% to 20.9%); E/DG, 10.7% (3.3% to 17.6%). The changes in serum total cholesterol and apolipoprotein B were similar but smaller than those in LDL-C. None of these treatment regimens induced significant overall changes in serum high-density lipoprotein cholesterol (HDL-C) or apolipoprotein A1 (Apo A1). The sequentially combined hormone treatments induced significant cyclical variations in HDL-C, with an increase during estrogen therapy and a decrease during combined therapy: E/LNG, 13.3% (7.4% to 19.4%); E/MPA, 6.9% (1.6% to 12.6%); E/DG, 10.3% (5.8% to 14.9%). No cyclical changes in HDL-C were found in the group receiving continuously combined hormone replacement therapy (E/CPA). The changes in Apo A1 parallel those in HDL-C.
Conclusion: All the treatment regimens produced changes in levels of serum lipids, lipoproteins, and apolipoproteins that may be considered favorable in terms of cardiovascular disease.