Rheumatoid factor IgM
Rheumatoid arthritis (RA) is a systemic autoimmune disease characterised by chronic joint inflammation, leading to irreversible deformity and loss of physical ability in advanced stages of the disease.
Rheumatoid factor (RF) is a protein produced in autoimmune diseases, namely rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus and others. Rheumatoid factor is generated in the joints and attacks own cells of the body, perceiving them as extraneous to the body, thus leading to chronic joint inflammation.
Determination of RF isotypes provides additional information on the diagnosis, differential diagnosis and course of RA.
High titer IgM RF
- is a vital sign of RA suitable for disease screening;
- correlates with disease activity;
- correlates with extraarticular damages, in particular with vasculitis;
- may be observed among individuals without RA, which is associated with an increased risk of developing RA.
Rheumatoid factor IgM is included in the international classification criteria for rheumatoid arthritis of 2010 (ACR/EULAR, 2010).