To help diagnose rheumatoid arthritis (RA) and differentiate it from other types of arthritis; to help evaluate the prognosis of a person with RA
Cyclic Citrullinated Peptide Antibody
When a healthcare practitioner suspects RA in someone who has joint inflammation with symptoms such as pain, stiffness, limited motion, and swelling in multiple joints
A blood sample drawn from a vein in your arm
Tell your healthcare practitioner about any medications and/or supplements you are taking. You may be instructed to stop taking multivitamins or dietary supplements containing biotin (vitamin B7) at least 8 hours before the blood draw.
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 irreversible 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 similar sensitivity to RF but a much higher specificity (95-98%) 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 test 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 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 healthcare 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?
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 Sjogren syndrome, and may be detected in infections such as tuberculosis.
- Should everyone be tested for CCP antibody?
No. CCP antibody is not recommended as a screening test. Like RF, it is best used to evaluate individuals whose clinical signs suggest RA or who have already been diagnosed with undifferentiated arthritis.
- Can I be tested for CCP antibody in my doctor's office?
Anti-CCP testing is widely available and may be tested for by your physician. This test may not be available in all laboratories but can be routinely sent to a reference laboratory.
- Will my CCP antibody ever go away?
Like other autoantibodies, once developed by the body's immune system, levels of CCP antibodies may fluctuate over time but will not go away. CCP antibody levels may decrease with treatment.
- 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 healthcare 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.