Plasma levels of fibroblast growth factor-23 are associated with muscle mass in haemodialysis patients.

Aim: Malnutrition is highly prevalent in haemodialysis (HD) patients, and it contributes to morbidity and mortality. Fibroblast growth factor-23 (FGF-23) and Klotho contribute to chronic kidney disease-mineral and bone disorder (CKD-MBD) in HD patients, but the role that these molecules play in determining nutritional status is currently unknown.

Methods: A cross-sectional study examining 77 HD patients was performed. The plasma concentrations of FGF-23 and soluble Klotho (s-Klotho) were studied to evaluate their association with muscle mass, which was investigated by abdominal muscle areas measured using computed tomography and by creatinine (Cr) production estimated using the Cr kinetic model.

Results: Plasma FGF-23 concentrations were significantly and positively correlated with abdominal muscle areas and Cr production (rho = 0.301, P < 0.01 and rho = 0.345, P < 0.01, respectively). In contrast, s-Klotho was not significantly correlated with these muscle mass indices and plasma FGF-23 concentrations. Multiple regression analyses showed that FGF-23 was a significant independent predictor of both muscle mass indices (P < 0.01 and P < 0.05, respectively).

Conclusion: Plasma FGF-23 concentrations were associated with muscle mass indices in HD patients. Our findings suggest that FGF-23 and nutritional status are linked and this link is most likely independent of s-Klotho.