Figure 2.

Effect of oral or i.v. iron therapy on ‘hepcidin block’ of iron release from macrophages. (A) Under normal circumstances, ∼25 mg of stored iron per day is transported out of macrophages to plasma transferrin by the iron transporter protein ferroportin. (B) In chronic disease, elevated levels of hepcidin cause degradation of ferroportin, restricting ferroportin-mediated transport to ∼15 mg iron/day, (C) The rate of iron absorption from iron therapy is inadequate to influence this ‘hepcidin block’. (D) I.v. iron therapy results in high intracellular iron levels which overcome the ‘hepcidin block’ by stimulating overexpression of ferroportin (modified from Aapro et al.⁴⁶).