Cyclic Citrullinated Peptide Antibody
Cyclic citrullinated peptide antibodies are autoantibodies produced by the immune system that are directed against cyclic citrullinated peptides (CCP). This test detects and measures anti-CCP antibodies in the blood.
Citrulline is naturally produced in the body as part of the metabolism of the amino acid arginine. However, in joints with rheumatoid arthritis (RA), this conversion may occur at a higher rate. Citrulline changes the protein structure and can trigger an immune response, producing autoantibodies against joint proteins. The CCP antibody test helps to diagnose RA and can be useful in identifying people with a more rapidly erosive form of the disease.
RA is a chronic, systemic autoimmune disease that causes inflammation, pain, stiffness, and destructive changes in the hands, feet, and other joints throughout the body. It can affect anyone at any age, but it usually develops between the ages of 40 and 60, and about 75% of those affected are women. The course of RA and its prognosis are variable. It may develop and progress slowly or rapidly. It may go into remission in some people and, in a few, it may go away. Left untreated, RA can shorten a person's lifespan and can, within a few years, leave many of those affected too disabled to work.
There are a variety of treatments available to minimize the complications of RA, but they depend on making an accurate diagnosis and on beginning treatment before the development of significant joint damage. Rheumatoid factor (RF) has been the primary blood test used to detect RA and distinguish it from other types of arthritis and other inflammatory processes. However, the sensitivity and specificity of RF are not ideal; it can be negative in people who have clinical signs of RA and positive in people who do not. Studies have shown that the CCP antibody test has a sensitivity and specificity that is equal to or better than RF and is more likely to be positive with early RA.
The 2010 Rheumatoid Arthritis Classification Criteria from the American College of Rheumatology (ACR) includes CCP antibody testing, along with RF, as part of its criteria for diagnosing rheumatoid arthritis. According to the ACR, CCP antibodies may be detected in about 50-60% of people with early RA, as early as 3-6 months after the beginning of symptoms. Early detection and diagnosis of RA allows healthcare providers to begin aggressive treatment of the condition, minimizing the associated complications and tissue damage.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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). Inflammatory markers may also be measured at this time, such as ESR and C-reactive protein (CRP).
Cyclic citrullinated peptide antibodies are autoantibodies produced by the immune system that are directed against cyclic citrullinated peptides (CCP). (See the "What is being tested?" section for more.)
CCP antibody testing may also be ordered to help evaluate the likely development of RA in people with undifferentiated arthritis – those whose symptoms suggest but do not yet meet the American College of Rheumatology (ACR) criteria for RA. According to ACR, approximately 95% of those with a positive CCP antibody will meet the criteria of RA in the future. Early detection of RA is essential for guiding treatment decisions.
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 a health practitioner 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 it is likely that they may develop a more rapidly progressive and 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 the person has 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?
Should everyone be tested for CCP antibody?
Can I be tested for CCP antibody in my doctor's office?
Will my CCP antibody ever go away?
What other tests might my doctor order in evaluating me for RA?
Your healthcare provider may choose to order an ESR and/or CRP, tests that detect inflammation. The health practitioner may also order a complete blood count (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, an analysis of joint fluid (synovial fluid) may be performed. In addition, your healthcare provider may also order antinuclear antibody (ANA) testing. A negative ANA helps exclude lupus and other systemic rheumatic diseases; the ANA may be positive in up to one-third of patients with RA.
On This Site
Elsewhere On The Web
American College of Rheumatology: Rheumatoid Arthritis
American College of Rheumatology: The Use of Anti-cyclic Citrullinated Peptide (anti-CCP) Antibodies in RA
Arthritis Foundation: Rheumatoid Arthritis
National Institute of Arthritis and Muscoskeletal and Skin Diseases: Rheumatoid Arthritis
Familydoctor.org: Rheumatoid Arthritis
Mayo Clinic: Rheumatoid Arthritis