FGF23 and X-linked hypophosphatemia: Biochemically, patients with XLH exhibited significantly higher levels of intact fibroblast growth factor 23 (iFGF-23) (211.96 ± 148.58 pg/mL vs. 43 ± 21.3 pg/mL; p < 0.001) and alkaline phosphatase (97.8 ± 43.6 U/L vs. 58.6 ± 12.8 U/L; p = 0.001), as well as reduced serum phosphorus levels (2.14 ± 0.5 mg/dL vs. 3.3 ± 0.5 mg/dl; p < 0.001) and tubular maximum reabsorption of phosphate per glomerular filtration rate (TmP/GFR) (2.12 ± 0.48 mg/dL vs. 3.3 ± 0.5 mg/dL; p < 0.001).