The rheumatoid factor (RF) test can help evaluate your RA diagnosis and prognosis.
Rheumatoid factor (RF) is the antibody responsible for the body attacking its own tissues in patients with rheumatoid arthritis (RA). In most cases, high levels of rheumatoid factor (20 IU/mL or above) occur in patients who have rheumatoid arthritis and/or Sjögren’s syndrome. The higher the RF, the worse the disease and the greater potential for joint damage and disability.
RF is evaluated when doctors suspect any form of arthritis. If someone is positive for RF, it doesn’t always mean that the patient has RA, but negative results do not rule it out either. However, in combination with RA symptoms, the RF test plays an important role in both diagnosis and prognosis of RA.