Background: Fibroblast growth factor-23 (FGF-23) is a phosphorus-regulating substance. Circulating FGF-23 levels increase markedly in dialysis patients and are independently associated with increased risk of mortality. Given the fact that cardiovascular disease is the leading cause of death in dialysis patients, the aim of this study was to test if elevated FGF-23 levels might be associated with left ventricular mass index (LVMI) and left ventricular index of myocardial performance (MPI) in maintenance haemodialysis patients.
Methods: In this cross-sectional study, plasma FGF-23 concentrations were measured using a C-terminal human enzyme-linked immunosorbent assay kit, and echocardiography was performed in 128 maintenance haemodialysis patients (65 women and 63 men, mean age: 55.5 ± 13 years, mean haemodialysis vintage: 52 ± 10 months, all patients are on haemodialysis thrice a week) and 40 control subjects (21 women and 19 men; mean age: 54 ± 11 years) with normal kidney function (eGFR > 90 mL/min/1.73 m(2)).
Results: Serum FGF-23 levels were elevated when compared with age- and gender-matched controls with preserved kidney function [(median 958 RU/mL; interquartile range 106-1894 RU/mL) vs (median 27 RU/mL; interquartile range 11-35), P < 0.0001]. Patients with a history of coronary artery disease and aortic valve calcifications had higher levels of log FGF-23 than those without (3.00 ± 0.22 vs 2.82 ± 0.26, P = 0.002; and 3.06 ± 0.19 vs 2.83 ± 0.26, P = 0.0001, respectively). Patients with MPI > 0.47 had higher serum FGF-23 levels than those with MPI < 0.47 [(median 1156 RU/mL; interquartile range 396-1894 RU/mL) vs (median 657 RU/mL; interquartile range 106-1102 RU/mL), P = 0.0001]. Significant correlations were recorded between log FGF-23 levels and LVMI (r = 0.281, P = 0,007) and MPI (r = 0.555, P = 0.0001). Multivariable-adjusted regression analyses revealed that increased log FGF-23 concentrations were independently associated with increased left ventricular mass index (30% increase per 1-SD increase in log FGF-23 concentration, P = 0.002) and increased MPI (28.5% increase per 1-SD increase in log FGF-23 concentration, P = 0.001).
Conclusions: Plasma FGF-23 concentration is independently associated with LVMI and MPI in maintenance haemodialysis patients. Further prospective studies are needed to clarify whether increased serum FGF-23 level is a marker or a potential mechanism for left ventricular involvement in patients with end-stage renal disease.