The links of hepcidin and erythropoietin in the interplay of inflammation and iron deficiency in a large observational study of rheumatoid arthritis

Summary Anaemia affects quality of life and radiographic outcome in rheumatoid arthritis (RA). In a cross‐sectional study with 779 patients, we assessed the prognostic potential of the major haematopoietic regulators, hepcidin and erythropoietin, comparing their serum concentrations with respect to different anaemia types, inflammatory activity, anti‐cytokine‐specific treatment effects and iron deficiency (ID) indices. The results showed that clinical disease activity was more closely associated with haemoglobin levels than with anti‐tumour necrosis factor‐alpha or interleukin 6 receptor effects. In ID, hepcidin was suppressed, independently of inflammation. Erythropoietin levels were inappropriately low in relation to the degree of anaemia, but, in contrast to low haemoglobin, not directly associated with joint damage progression. Hepcidin and erythropoietin levels are intimately connected with inflammation and ID. Interventional studies on these important targets are already in progress.