Fibroblast growth-factor 23 and vitamin D are associated with iron deficiency and anemia in children with chronic kidney disease

Background This cross-sectional study investigates the association of fibroblast growth-factor 23 (FGF23) and other bone mineral parameters with iron status and anemia in pediatric chronic kidney disease (CKD). Methods Serum calcium, phosphorus, 25-hydroxyvitamin D (25(OH)D), intact parathormone, c-terminal FGF23, a-Klotho, iron (Fe), ferritin, unsaturated iron-binding capacity, and hemoglobin (Hb) were measured in 53 patients from 5 to 19 years old with GFR 100 ng/mL, TSAT ≤ 20%) were observed in 32% and 7.5% of patients, respectively. In CKD stages 3–4 (36 patients), lnFGF23 and 25(OH)D were correlated with Fe (rs = − 0.418, p = 0.012 and rs = 0.467, p = 0.005) and TSAT (rs = − 0.357, p = 0.035 and rs = 0.487, p = 0.003) but not to ferritin. In this patient group, lnFGF23 and 25(OH)D were correlated with Hb z -score (rs = − 0.649, p