Comparative study of the levels of B2-microglobulin in serum and synovial fluid in patients with rheumatoid arthritis and osteoarthritis

B2-microglobulin [B2-m], as a low molecular weight protein, was evaluated in serum and synovial fluid of 10 patients with rheumatoid disease [RD], 10 patients with osteoarthritis [OA], and 10 age and sex matched controls. These investigations were done after excluding all patients with renal diseases. It was found that the serum level of B2-m was significantly elevated, in both RD and OA with more increase in the former, when compared with the control group. The synovial fluid/serum ratio of B2-m was a better diagnostic tool that could be used for differentiation between RD and OA, rather than using the serum level of B2-m in each disease alone