We were interested in investigating whether the levels of the soluble receptors sRANKL, sRAGE, and OPG are affected by the distribution of RA patients in subgroups according to sTfR-F index and hemoglobin levels and in examining their correlation with indicators of iron metabolism, disease activity, and autoimmune and inflammatory changes in these subgroups. The gene discussed is TFRC; the disease is rheumatoid arthritis.