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. Here, TNFRSF11B is linked to rheumatoid arthritis.