National differences in lipid response to postmenopausal hormone replacement therapy

Objective: To compare the response of serum lipids and lipoproteins to the transdermal hormone replacement therapy (HRT) in five European countries. Methods: Five-hundred and sixty-seven healthy postmenopausal women from Belgium, Finland, the Netherlands, Sweden, and the UK received transdermal estradiol 50 μg daily for 12 months. In addition, two groups received transdermally norethisterone acetate (NETA) continuously, two groups sequentially (170 or 350 μg/day); one group received sequentially oral NETA (1 mg/day), and one group dydrogestrone (20 mg/day). Serum total cholesterol, HDL-, HDL2-, LDL-cholesterol, lipoprotein(a) (Lp(a)), and triglycerides were assessed before and at the end of treatment. Results: No significant national differences existed in the pretreatment levels of lipids and lipoproteins. Mean cholesterol, LDL, Lp(a), and triglycerides decreased during HRT, and HDL and HDL2 increased. Individual changes in responses to HRT were strongly dependent on pretreatment values. In this regard, British women differed from the others: their cholesterol, HDL, HDL2, and Lp(a) responses, when related to the pretreatment levels, were smaller than those of the others. Conclusion: A national difference discovered in response of serum lipids to HRT calls for caution in generalization of lipid data from one nation to another during HRT.