Rheumatoid Factors (RF) are autoantibodies that react with individuals own immunoglobulin. These antibodies are usually directed against the Fc fragment of the human IgG. RF have been associated with three major immunoglobulin classes: IgM, IgG, and IgA.
Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting primarily the joints and periarticular tissues. Rheumatoid factor is detected in 60-80% of cases of diagnosed rheumatoid arthritis. However, it is also detectable sometimes in the serum of patients with Systemic Lupus Erythematosus (SLE) and in certain non-rheumatic conditions. Elevated values may also be observed in normal elderly population.
Positive result: An agglutination of the latex particles suspension will occur within two minutes, indicating a RF level of more than 18 IU/ml.
Negative result: No agglutination of the latex particles suspension within two minutes.
