Suppression of hepcidin production accompanied by improvement in inflammatory anemia as well as disease activity in 9 MCD patients treated with anti–IL-6R antibody. Long-term effects were assessed at 1.5, 3, 6, and 12 months after the start of tocilizumab therapy. Serum hepcidin-25 was quantified with a liquid chromatography-tandem mass spectrometry-based assay system. Other serum parameters were measured with standard laboratory techniques. (A) Serum level of hepcidin-25. (B) Hb. (C) Serum iron. (D) RBCs. (E) Ferritin. (F) MCV. (G) CRP. (H) EPO.