Rheumatoid Factor (RF) is an important marker often used in the diagnosis and management of Rheumatoid Arthritis (RA). However, elevated levels of RF are not exclusive to RA and can be indicative of various other health conditions. Among these are chronic infections such as viral hepatitis B and C, inflammatory lung diseases like sarcoidosis, mixed connective tissue disease, Sjogren syndrome, and systemic lupus erythematosus. Furthermore, RF levels can be influenced by other factors including Sjögren’s disease, lupus, chronic bacterial infections like syphilis or tuberculosis, viral infections (including hepatitis C, HIV, and herpes), parasitic infections (such as malaria), cancer, sarcoidosis, and cirrhosis.
Per the National Library of Medicine, additional conditions associated with elevated RF levels include Hepatitis C, mixed connective tissue diseases, mixed cryoglobulinemia, primary sclerosing cholangitis, sarcoidosis, Sjogren syndrome, subacute infective endocarditis, and systemic lupus.
RF is comprised of antibodies with various isotypes and affinities directed against the Fc portion of immunoglobulin G. The commonly mentioned RF is an IgM RF, although other immunoglobulin types including IgG and IgA are also found, albeit rarely.
Rheumatoid arthritis itself is a systemic autoimmune disease characterized by inflammatory arthritis and extra-articular involvement. This chronic inflammatory disorder is often the result of interactions between genetic and environmental factors, including tobacco, primarily involving synovial joints. Whether or not a patient with RA possesses the rheumatoid factor is another type or classification of the disease. Rheumatoid factor is an antibody used to determine the presence of the autoimmune disorder that causes rheumatoid arthritis, in addition to testing positive for anti-CCPs.
For more comprehensive information, refer to the Mayo Clinic, Medical News Today, HealthCentral, and StatPearls – NCBI Bookshelf.
