Rheumatoid factor is an
antibody, a protein made by the immune cells to
specifically recognize and help to destroy bacteria and viruses. Each person
makes thousands of different antibodies, each of which can specifically
recognize thousands of different foreign substances that may attack the
Rheumatoid factor (RF) can be detected with a blood test. Your doctor
may order this blood test if there is a suspicion that you might have
rheumatoid arthritis or if you are being tested for certain other
autoimmune diseases. People with rheumatoid arthritis
often have high levels of RF. So a finding of a high RF can support a
diagnosis of rheumatoid arthritis in a person with other symptoms of rheumatoid
arthritis, such as joint pain with joint swelling and morning stiffness.
However, elevation of RF in the absence of symptoms has no bearing on the
likelihood that you will develop rheumatoid arthritis.
All people make RF antibodies as part of the normal process of
responding to infection. If sensitive enough measures are used, it can be shown
that everyone has rheumatoid factors, and these may be elevated normally
following infection, blood transfusion, or other events that stimulate the
activity of the
immune system. As the name implies, though,
rheumatoid factor was first identified in patients with rheumatoid arthritis
because these patients tend to make a great excess of these antibodies. Higher
elevation of RF has been associated with a more aggressive disease progression
in rheumatoid arthritis.
Primary Medical Reviewer
Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer
Nancy Ann Shadick, MD, MPH - Internal Medicine, Rheumatology
How this information was developed to help you make better health decisions.