Question
My mother was recently stricken with the near crippling onset of RA that came on over a 2 week period. In November her rheumatoid factor antibody was 44; she was referred to specialist for treatment. My question has to do with understanding the RA test. She had it rechecked this week and it is now over 2000, is this normal, is this any indication of severity of disease or indication of efficacy ot this treatment? Do the test values help in monitoring therapy?
Answer
There are 2 autoantibody tests that can be helpful in diagnosing rheumatoid arthritis. Rheumatoid factor (RF) is the older of the two tests. Unfortunately, this test is not specific for rheumatoid arthritis and can be seen in other medical conditions such as chronic infections (endocarditis, hepatitis C) and paraproteinemias. Anti-CCP antibodies are much more specific for rheumatoid arthritis. That is these antibodies are not generally found in other conditions. We use the measurement of antibodies to aid in the diagnosis of rheumatoid arthritis and to help with determining prognosis. Individuals who have rheumatoid arthritis and these autoantibodies are more likely to have erosive disease. However, we do not use the antibody titers to determine disease activity over time. Disease activity is determined by a combination of number of tender joints, swollen joints, lab studies, and patient and physician global assessment.
