LAUSR

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) has been recognized as a common complication and arises early in the course of CKD. Osteoporosis can be one form of renal osteodystrophy, one component of the bone abnormalities of CKD-MBD. Fibroblast growth factor 21 (FGF21) is increased progressively with a decline of renal function and higher FGF21 levels predict high all-cause mortality in hemodialysis patients. In recent studies, FGF21 has been approved to exert an inverse effect on bone mineral density. Hence, our study was performed to investigate the relationship and role of FGF21 in osteoporosis in our hemodialysis (HD) patients cohort. We screened HD patients in Nanjing Zhongda Hospital and The First People’s Hospital of Changzhou according to a strict inclusion criteria and exclusion criteria. We recorded demographic information, blood data before dialysis and serum FGF21, FGF23 levels and measured the CT-attenuation values (in Hounsfield units (HU)) of trabecular bone in L1 on axial images to evaluate the severity of osteoporosis. We used univariate analyses to compare the differences between two groups. Meanwhile, bivariate correlation analyses were performed to assess the correlation of L1 attenuation with serum FGF21, FGF23 and other clinical parameters. Stepwise multivariate linear regression analyses were employed to evaluate variables independently associated with attenuation values. We constructed ROC curves to calculate the AUC and compared the prognostic value of every independently associated factor or united factor to osteoporosis. All analyses were two-tailed, and a P < 0.05 was considered to be statistically significant. SPSS Software, version 18.0 was used for all statistical analyses. 339 HD patients from two big HD centers in China that met our standards were screened. The mean age of HD patients was 56.79 ± 15.60 years. 339 HD patients were divided into two groups osteoporosis (n = 98) and non-osteoporosis (n = 241) on the basis of HU level (L1 attenuation ≤ 135 HU). Remarkably, serum FGF21 were higher in osteoporosis compared to non- osteoporosis in HD patients (median 640.86 pg/ml vs. 245.46 pg/ml, P < 0.01). We also divided HD patients into two groups according to tertiles of serum FGF21 levels. Moreover, attenuation levels were negative associated independently with serum FGF21 (r=-0.136, P<0.05). To evaluate the different values of independent associated or united factors in predicting osteoporosis, receiver operating characteristic (ROC) curves was constructed. The area under the curve (AUC) for FGF21 combined with age yielded a marked increment (AUC=0.836, P=0.000) with a good sensitivity (93.8%). In conclusion, elevated FGF21 level has a positive relationship with the incidence of osteoporosis in HD patients. Simultaneously, FGF21 in combination with age can be a predictive parameter of osteoporosis in HD patients.