In addition to clinical evaluation involving a discussion of symptoms and a physical exam, laboratory and non-laboratory testing is often done to help diagnose rheumatoid arthritis (RA), to distinguish it from other forms of arthritis and conditions with similar symptoms, and to evaluate its severity. Testing can also be used to monitor the condition, its potential complications, response to treatment, and to monitor for potential side effects associated with some treatments.
- Rheumatoid factor (RF) – used to help diagnose RA; it is present in significant concentrations in most people (about 80%) with RA but can also be present in people with other diseases and in a small percentage of healthy people; when positive in someone with symptoms of RA, this test can be useful to confirm the diagnosis.
- Cyclic citrullinated peptide (CCP) antibody – may be used to help diagnose RA, especially early in the disease – potentially before symptoms even appear – and in people who are RF-negative; found in 60-70% of people with RA; when used with the RF test, CCP results can help confirm a diagnosis of RA.
- Antinuclear antibody (ANA) – this test is used to screen for certain autoimmune disorders, sometimes including RA, but is most often used as one of the tests to diagnose systemic lupus erythematosus (SLE).
- Erythrocyte sedimentation rate (ESR) – this test shows the presence of inflammation in the body and the activity of the disease. It is used to help diagnose RA and to evaluate and monitor the condition. ESR will be increased in RA but not in osteoarthritis.
- C-reactive protein (CRP) – this test also indicates inflammation and tests for the activity of the disease. It may be used to help diagnose RA and to evaluate and monitor the condition. An increased level of CRP occurs in RA but not in osteoarthritis.
- Complete blood count (CBC) – this is a group of tests used to help evaluate the person's red and white blood cells and hemoglobin to help monitor for anemia and/or a decrease in white blood cells.
- Comprehensive metabolic panel (CMP) – this is a group of tests that may be used to help evaluate and monitor kidney and liver function.
- X-ray – used to help diagnose RA and monitor joint damage but will not usually show significant changes early in the disease; can be used to rule out other causes of joint pain.
- Ultrasound and MRI – may be used to help detect changes in the joints earlier in the disease.