Objectives: To examine the associations of residual endogenous estradiol (E2) to bone mineral density (BMD) and lipid concentrations in elderly women.
Methods: Subjects consisted of 59 elderly postmenopausal women with vertebral or femoral osteoporosis. BMD was measured at L2-4 and femoral neck by dual-energy X-ray absorptiometry (DEXA). Residual E2 concentrations were assessed by a sensitive radioimmunoassay. Data were expressed as mean +/- S.E.M.
Results: The age of the subjects was 65.2 +/- 0.8 years with 18.9 +/- 1.0 years postmenopausal. The mean residual E2 concentration was 6.0 +/- 0.5 pg/ml. There was a correlation between E2 levels and BMD at L2-4 (r = 0.32, P < 0.01) while no association was found at the femoral neck. The association between E2 and L2-4 BMD persisted after adjusting for years since menopause and body weight (r = 0.33, P < 0.05). With regard to serum lipid concentrations, no association of serum total cholesterol, LDL-cholesterol, HDL-cholesterol or triglyceride concentrations with residual E2 was found.
Conclusions: Our findings confirm the role of residual endogenous E2 in the determination of bone mass in postmenopausal women with osteoporosis. The effect of residual E2 appears to be skeletal specific and possess no association with serum lipid concentrations.