Fukao W, et al. - In this prospective randomized study, researchers compared the impact of oral or intravenous iron administration on serum levels of intact (I-)fibroblast growth factor-23 (FGF23) and C-terminal (C-)FGF23 in iron-deficient patients on maintenance hemodialysis (MHD). Analysis of changes in I-FGF23 and C-FGF23 after 10 weeks of treatment revealed decreased C-FGF23 levels as a result of iron administration in these patients. With intravenous iron administration, I-FGF23 levels increased but this effect was not induced by oral iron administration. the use of oral iron was recommended in cases where the goal of chronic kidney disease-mineral and bone disorder therapy is to reduce I-FGF23 levels.