The association of serum osteoprotegerin and osteoporosis in postmenopausal hemodialysis patients: a pilot study

Abstract

Aim: Osteoprotegerin (OPG) is a potent inhibitor of osteoclasts and plays an important role in bone metabolism. Relatively high serum levels of OPG have been observed in postmenopausal women with osteoporosis compared with age-matched controls. No data, however, are available on the relationship between low bone density and serum OPG levels in postmenopausal hemodialysis (HD) patients.

Methods: The enrolled subjects included 28 postmenopausal HD patients and 28 age-matched postmenopausal women with normal renal function as controls. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DEXA) in both hips. Low BMD was defined as femoral neck T-score <-2.5. Serum OPG levels were measured using a commercial enzyme-linked immunosorbent assay (ELISA) kit.

Results: Eight of the age-matched postmenopausal controls (28.6%) and 12 of the postmenopausal HD patients (42.9%) had low BMD. There was no statistically significant difference in low BMD between postmenopausal HD patients and age-matched postmenopausal patients (p = 0.263). The serum OPG level was significantly higher in the postmenopausal HD group (p < 0.001). Increased serum OPG (p = 0.017) and decreased serum albumin (p = 0.021) were significantly correlated with low BMD in postmenopausal HD patients. Univariate linear regression analysis showed that serum albumin (r = -0.455, p = 0.015) was negatively correlated, whereas age (r = 0.423, p = 0.025) and the length of time since menopause (r = 0.397, p = 0.036) were positively correlated with the serum OPG level in postmenopausal HD patients. Multivariate forward stepwise linear regression analysis showed that serum OPG (adjusted R(2) = 0.262, p = 0.003) was an independent predictor of low BMD in postmenopausal HD patients and explained 26.2% of the variance.

Conclusions: Serum OPG is associated with low BMD in postmenopausal HD patients.