Considering the fact that FGF23 decreases 1,25-dihydroxyvitamin D3 levels by inhibiting CYP27B1 (1-α-hydroxylase) and by stimulating CYP24A1 (24-hydroxylase)10,11, vitamin D deficiency may be a potential mechanistic link that can explain the relationship between FGF23 and anemia. Here, CYP27B1 is linked to vitamin D deficiency.