What is Rheumatoid factor (RF)?
Rheumatoid factor (RF) is an autoantibody that is an antibody that targets the body's own proteins. In the case of RA, RF targets IgG antibodies and forms immune complexes, leading to inflammation in the joints. The formation of RF antibodies in the blood can indicate autoimmune disease, which means that the body starts to fight its own cells and its own immune system. RF can also be detected in connection with infection without always being connected with rheumatic disease and is also present in the blood of approximately 5% of completely healthy people.
Why is Rheumatoid factor analyzed?
Diagnosing rheumatoid arthritis (RA): A positive RF test can be one of several factors that indicate a person may have rheumatoid arthritis. It is used along with other clinical and laboratory tests to confirm the diagnosis of RA.
Monitoring: The RF test can be used to monitor disease activity and treatment effectiveness in people who have already been diagnosed with RA.
Evaluate other rheumatic diseases: RF levels can sometimes be elevated in other autoimmune diseases and rheumatic conditions even if they are not necessarily specific to RA. It can help guide doctors in the diagnosis of various diseases.
What does an elevated value of Rheumatoid factor mean?
An elevated RF value can mean the following:
Rheumatoid arthritis (RA): A positive RF test can support the diagnosis of RA. The higher the RF levels, the stronger the association with RA may be.
Other autoimmune diseases: High RF levels can also occur in other autoimmune diseases such as systemic lupus erythematosus (SLE), Sjogren's syndrome and systemic sclerosis.
Infections: RF levels may temporarily increase in certain infections especially chronic infections such as hepatitis C.
Age: Older people sometimes have higher RF levels even if they have no symptoms of the disease.
