Rheumatoid Factor (RF) Test

The RF test is used for the qualitative screening and semiquantitative determination of Rheumatoid Factor (RF) in serum to help diagnose Rheumatoid Arthritis (RA). RF is associated with autoimmune diseases such as Rheumatoid Arthritis and Sjogren’s Syndrome.

RA is a chronic, systemic disease characterized by joint swelling and pain, as well as inflammatory and degenerative processes involving cartilage, synovial membrane, or muscle tissue. Early therapy minimizes irreversible damage to the joints, so a prompt diagnosis is crucial. A characteristic of RA is the presence of a reactive group of proteins in the blood and synovial fluid, collectively known as the RF. Many investigators think that the RF are antibodies directed against “altered” human gamma globulin (IgG). The RF are found in 70-100% of definite RA cases. The occurrence of RF in osteoarthritis or rheumatic fever is less than 2% and 3%, respectively. However, it should be noted that RF has also been reported in non-rheumatic diseases such as pulmonary tuberculosis, bacterial endocarditis, syphilis, as well as others.

The principle of the RF Test is based on the reaction between RF in serum with the IgG coated onto latex particles, resulting in visible agglutination.