How is it used?
A cyclic citrullinated peptide (CCP) antibody test may be ordered along with or following a rheumatoid factor (RF) test to help diagnose rheumatoid arthritis (RA) and to assess the severity and probable course of the disease (prognosis). CCP antibody may also be ordered to help evaluate the likely development of RA in people.
When is it ordered?
A CCP antibody test is primarily ordered along with an RF test when someone has signs and symptoms that may be due to previously undiagnosed inflammatory arthritis or has been diagnosed with undifferentiated arthritis. It may be ordered as a follow-up test to a negative RF test when clinical signs and symptoms lead the doctor to suspect RA. RA usually affects multiple joints symmetrically. Signs and symptoms may include:
- Painful, warm, swollen joints of the hands and wrists most commonly
- Pain sometimes affecting elbows, neck, shoulders, hips, knees, and/or feet
- Stiffness of affected joints in the morning that improves during the course of the day
- Development of nodules under the skin, especially at the elbows
- A general feeling of being unwell (malaise)
What does the test result mean?
When people with signs and symptoms of arthritis are positive for both CCP antibody and RF, it is very likely that they have RA and that they may develop a more severe form of the disease. When people are positive for CCP antibody but not RF, or have low levels of both, and have clinical signs that suggest RA, then it is likely that they have early RA or that they will develop RA in the future.
When individuals are negative for CCP antibody but have a positive RF, then the clinical signs and symptoms are more vital in determining whether they have RA or some other inflammatory condition. When someone is negative for both CCP antibody and RF, then it is less likely that they have RA. It must be emphasized, however, that RA is a clinical diagnosis and may be made in the absence of positive tests for autoantibodies.
Is there anything else I should know?
The CCP antibody test is relatively new. It is becoming more widely used but is still less frequently ordered than the RF test.
CCP antibodies are rarely found in other autoimmune conditions, such as lupus, Graves' disease and Sjögren's syndrome, and may rarely be detected in viral infections such as hepatitis C.
Will my CCP antibody ever go away?
Like other autoantibodies, once developed by the body's immune system, levels of CCP may fluctuate over time but will not go away.
What other tests might my doctor order in evaluating me for RA?
Your doctor may choose to order an ESR and/or CRP, tests that detect inflammation. They may also order a CBC to check for a high white blood cell count, another sign of inflammation and to check for anemia, a condition common in people with RA. For added information, imaging, such as an X-ray and an analysis of joint fluid (synovial fluid) may be performed to evaluate the affected joints. In addition, your doctor may also order antinuclear antibody (ANA) testing. A negative ANA helps exclude SLE and other systemic rheumatic diseases; the ANA may be positive in up to one-third of patients with RA.