ABSTRACT
Objective: In this quasi-experimental study, we aimed to measure the effect of hormone replacement therapy (HRT) on serum lipid, apolipoprotein AI, apolipoprotein B, and lipoprotein (a). The study had three objectives: to replicate previous studies' findings on the effect of HRT on lipid and lipoprotein profiles; to integrate possible effects of dietary and exercise improvements (considered as independent predictors), covariates, and interaction variables; and to report effect sizes capable of estimating the impact of HRT on each outcome variable of the study. Material and Methods: The effect of HRT on serum lipid, apolipoprotein AI, apolipoprotein B, and lipoprotein (a) was determined in a case group of 86 postmenopausal women compared with that in a control group of 97 age-matched women who were not receiving HRT and who were not menopausal. Results: HRT had the expected salutary effect on all measured variables, except for apolipoprotein AI. The largest effect size was observed for high-density lipoprotein cholesterol, suggesting the need for replication and if necessary, further investigation of why HRT might be particularly beneficial for highdensity lipoprotein cholesterol levels of postmenopausal women. Conclusion: Finally, the study found neither an independent nor interactive effect of diet or exercise on the effect of HRT.