FP618
THE ASSOCIATION OF FIBROBLAST GROWTH FACTOR - 23 AND BONE TURNOVER MARKERS ON HEMODIALYSIS PATIENTS

INTRODUCTION AND AIMS: Circulating fibroblast growth factor 23 (FGF23) is associated with higher all-cause mortality and cardiovascular risks in hemodialysis patients. Beyond the FGF23 on myocardial hypertrophy, FGF23 may have effect on bone mineralization. Study showed the direct action of FGF23 on bone independent of serum phosphate levels. In order to distinguish between these association, we measured serum concentrations of FGF23, parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium, phosphate, and markers of bone turnover markers (osteocalcin, osteoprotegerin, soluble receptor activator of nuclear factor - κβ ligand [sRANKL]) in prevalent hemodialysis (HD) patients.

METHODS: We enrolled HD patients from two hospitals (one medical center and one local hospital) at the same healthcare system in Taiwan. All patients received regular HD thrice a week through the use of automated volumetric machines. Each HD session lasted 3-4 h and involved using high-flux dialyzers. The blood flow rate is controlled between 250 and 300 ml/min, and the dialysate flow is maintained at 500 ml/min. The FGF-23 and bone turnover markers were measured by luminex multiplex technology using Bone Hormone Panel (HBNMAG-51K, Millipore Corporation, Billerica, MA, USA). Serum intact PTH and ALP were measured using a commercial enzyme-linked immunosorbent assay (ELISA).

RESULTS: There were 341 HD patients with mean age 59.2 ± 11.5 years, 53.4% male, 41.9% diabetes mellitus, 75.1% hypertension, and 33.4% ischemic heart disease in our study cohort. FGF23 concentrations were increased in all HD patients, positive correlated with serum phosphate level and serum calcium phosphate ion product (Ca X P). As for bone turnover markers, serum FGF-23 was positive correlated with osteocalcin (P = 0.003, r² = 0.161) and sRANKL (P = 0.009, r² = 0.145), which were produced by osteoblasts. However, serum FGF23 level was negative correlated with ALP (P < 0.001, r² = -0.350).

CONCLUSIONS: Serum FGF23 level was positive correlated with osteoblast activity markers but negative correlated with osteoblast differentiation and mineralization. This clinical observation study may observe the effect that FGF23 inhibit osteoblast formation and stimulate slightly osteoblast activity.