Serum Irisin Level Is Positively Associated with Bone Mineral Density in Patients on Maintenance Hemodialysis

Abstract

Background. Irisin is a circulating hormone-like myokine that plays an important role in bone metabolism. We performed a cross-sectional study to investigate whether serum irisin levels correlated with bone mineral density (BMD) in patients on maintenance hemodialysis (MHD). Methods. Blood samples were obtained from 80 patients on MHD, and serum irisin concentrations were determined using a commercially available enzyme-linked immunosorbent assay. BMD was measured by dual-energy X-ray absorptiometry of the L2–L4 vertebrae. Results. In the study cohort, 10 (12.5%) and 19 (23.8%) patients had osteoporosis and osteopenia, respectively, and 51 (63.75%) patients had normal BMD. Lumbar T-score was negatively associated with body height ( $P=0.010$ ), body weight ( $P=0.002$ ), body mass index (BMI, $P=0.010$ ), and serum irisin ( $P<0.001$ ) and was positively associated with advanced age ( $P=0.031$ ), female sex ( $P=0.001$ ), alkaline phosphatase (ALP, $P=0.010$ ), urea reduction rate ( $P=0.018$ ), and fractional clearance index for urea ( $P=0.020$ ). Multivariable forward stepwise linear regression analysis revealed that high serum logarithmically transformed irisin (log-irisin, β = 0.450, adjusted R2 change = 0.258; $P<0.001$ ), female sex (β = −0.353, adjusted R2 change = 0.134; $P<0.001$ ), and serum ALP level (β = −0.176, adjusted R2 change = 0.022; $P=0.049$ ) were significantly and independently associated with lumbar BMD in patients on MHD. Conclusions. In addition to female sex and serum ALP level, serum irisin level was positively associated with lumbar BMD in patients on MHD.