How Is Rheumatoid Arthritis Diagnosed?
The diagnosis of rheumatoid arthritis is based on a combination of factors, including:
- The specific location and symmetry of painful joints, especially the hand joints.
- The presence of joint stiffness in the morning.
- Presence of bumps and nodules under the skin (rheumatoid nodules).
- Results of X-ray tests that suggest rheumatoid arthritis.
- Positive results of a blood test called the rheumatoid factor.
Most, but not all, people with rheumatoid arthritis have the rheumatoid-factor antibody in their blood. (Rheumatoid factors are actually antibodies that bind other antibodies.) Rheumatoid factor may sometimes be present in people who do not have rheumatoid arthritis. Other diseases can also cause the rheumatoid factor to be produced in the blood. Therefore, the diagnosis of rheumatoid arthritis is based on a combination of joint abnormalities as well as laboratory information and not just the presence of the rheumatoid factor in the blood.
A newer, more specific blood test for rheumatoid arthritis is the cylic citrulline antibody test, also called anti-CCP. When positive, it is highly suggestive of rheumatoid arthritis. The presence of anti-CCP antibodies implies a tendency toward a more aggressive form of rheumatoid arthritis.
People with rheumatoid arthritis may have a mild anemia. Blood tests may also reveal an elevated erythrocyte sedimentation rate (ESR) or elevated C-reactive protein (CRP) levels, which are markers of inflammation.
Some people with rheumatoid arthritis may also have a positive antinuclear antibody test (ANA). This test is indicative of the fact that rheumatoid arthritis is an autoimmune disease and sometimes overlaps with other autoimmune disorders.