Context: Fibroblast growth factor (FGF)-23 is produced in bone, and circulating levels are markedly elevated in patients with end-stage kidney disease, but the relationship between plasma levels of FGF-23 and bone histology in dialysis patients with secondary hyperparathyroidism is unknown.
Objective: The aim of the study was to evaluate the correlation between plasma levels of FGF-23 and bone histology in pediatric patients with end-stage kidney disease who display biochemical evidence of secondary hyperparathyroidism.
Design: We performed a cross-sectional analysis of the relationship between plasma FGF-23 levels and bone histomorphometry.
Setting: The study was conducted in a referral center.
Study participants: Participants consisted of forty-nine pediatric patients who were treated with maintenance peritoneal dialysis and who had serum PTH levels (1st generation Nichols assay) greater than 400 pg/ml.
Intervention: There were no interventions.
Main outcome measure: Plasma FGF-23 levels and bone histomorphometry were measured.
Results: No correlation existed between values of PTH and FGF-23. Bone formation rates correlated with PTH (r = 0.44; P < 0.01), but not with FGF-23. Higher FGF-23 concentrations were associated with decreased osteoid thickness (r = -0.49; P < 0.01) and shorter osteoid maturation time (r = -0.48; P < 0.01).
Conclusions: High levels of FGF-23 are associated with improved indices of skeletal mineralization in dialyzed pediatric patients with high turnover renal osteodystrophy. Together with other biomarkers, FGF-23 measurements may indicate skeletal mineralization status in this patient population.