The influence of Visfatin, RBP-4 and insulin resistance on bone mineral density in women with treated primary osteoporosis

The impact of the two adipokines, visfatin and retinol-binding protein 4 (RBP-4) on bone mineral density (BMD) has been analysed in various studies with conflicting results. Visfatin is highly expressed in visceral fat with stimulatory effect on osteoblast proliferation and inhibition on osteoclast formation, while RBP-4 acts as a transporter protein for retinol, associated with changes in insulin sensitivity, independent of obesity, with no consensus on its effect on bone metabolism. We evaluated the relationship between serum concentrations of visfatin, RBP-4, markers of insulin resistance and current BMD in treated postmenopausal osteoporosis (PO). Demographics, previous treatment, metabolic status, anthropometry, serum Alkaline phosphatise (ALP), visfatin, RBP-4, the HOMA IR (homeostatic model assessment of insulin resistance) index and BMD were evaluated in 61 subjects with PO. Statistical analysis used SPSS v. 25.0, with a level of significance α = 0.05. Regression models were constructed to evaluate the relationship between adipokines and BMD, adjusting for covariates. In multilinear regression analysis, the strongest predictor for current BMD was a previous BMD, followed by ALP and age. RBP4 and HOMA IR were significant predictors, while visfatin had no significant effect. A significant correlation between body mass index (BMI) and BMD at the femoral neck was observed. ALP was negatively correlated with BMD and visfatin positively with RBP4. Data indicate a positive relationship between BMD and RBP-4, an inverse relationship between markers of insulin resistance, bone turn-over and current BMD. No significant effect of visfatin on BMD was observed.