FGF23 and hypophosphatemia: (Fig. 1) Laboratory tests revealed hypophosphatemia (0.32 mmol/L), elevated alkaline phosphatase (429 U/L, normal range: 45 to 125 U/L), 25 (OH) D deficiency (16.25 ng/mL, normal range: >30), and an elevated level of FGF23 (158.7 pg/mL, normal range: 23.3 to 95.4 pg/mL).