Background: The effects of oral estrogen therapy (ERT) on lipids and metabolic parameters are well known, in contrast to the effects of subcutaneously administered estrogen, particularly high concentrations of estrogen. We examined metabolic parameters in cohorts of women with and without subcutaneous estrogen therapy with concomitant supra-normal concentrations of estradiol (SE).
Methods: Lipids and lipoprotein concentrations, low density lipid (LDL) subfractions, and activity of hepatic lipase (HL) were assessed in 30 menopausal women with SE and 19 control subjects not using ERT, matched for body mass index and age.
Results: Waist-hip ratio (WHR) and fasting insulin (FI) concentrations were lower in the SE group compared with the women not on ERT (P < 0.05). The concentrations of triglyceride and high density lipid (HDL) cholesterol were similar (P > 0.1), whereas total cholesterol (P < 0.05), LDL cholesterol (P < 0.05), and HL activity (P < 0.01) were lower in the SE group. Concentrations of the large, buoyant LDL I subfraction were significantly lower in the SE group (P < 0.05), but there was no difference in LDL III concentrations.
Conclusions: Women with SE have similar triglyceride and HDL cholesterol levels but lower LDL cholesterol concentrations compared with post-menopausal women not taking ERT. The observations that the SE group showed reduced fasting insulin and WHR suggest that supra-normal circulating concentrations of estradiol, delivered subcutaneously, may beneficially influence insulin metabolism.