Anti-CCP Antibodies
Anti-CCP· also: ACPA, anti-CCP2, CCP antibodies
Clinical Overview
Anti-CCP (anti-cyclic citrullinated peptide) antibodies are highly specific autoantibodies for Rheumatoid Arthritis (RA). They target citrullinated proteins produced during inflammation. Anti-CCP is more specific for RA than Rheumatoid Factor and can be detected years before clinical symptoms appear — making it valuable for early diagnosis and prognosis.
Why This Test Matters
Anti-CCP has approximately 95% specificity for RA with sensitivity of 60–75% — similar sensitivity to RF but far superior specificity. A positive anti-CCP in a patient with joint symptoms is strong evidence for RA. Anti-CCP positivity predicts a more erosive, aggressive disease course. It is now included as a high-weight criterion in the 2010 ACR/EULAR RA classification criteria. Anti-CCP testing has largely supplanted RA-specific tests because it avoids false positives from hepatitis C, Sjögren's, and other non-RA conditions that elevate RF.
Reference RangesWHO/IFCC standards
| Reference Range | Unit | Notes |
|---|---|---|
| 0 – 20 | U/mL | Negative <20; Positive ≥20 |
What Causes Abnormal Results?
High Anti-CCP Causes
- Rheumatoid Arthritis (RA) — primary indication, highly specific
- Rarely: Sjögren's syndrome, SLE, psoriatic arthritis (much lower frequency than RA)
Low Anti-CCP Causes
- Approximately 25–40% of RA patients are anti-CCP negative (seronegative RA)
- Seronegative RA tends to be less severe but still progressive
Signs & Symptoms to Watch For
How to Prepare for This Test
No fasting required. For best diagnostic accuracy, order anti-CCP alongside RF, CRP, and ESR. Anti-CCP requires a standard venous blood sample.
Factors That Can Affect Results
- Very few false positives compared to RF — hepatitis C, elderly age, and other conditions do NOT elevate anti-CCP significantly
- Anti-CCP result is not affected by recent corticosteroid or DMARD therapy at the time of sampling
Related Topics
Frequently Asked Questions
Can anti-CCP predict how severe my rheumatoid arthritis will be?
Yes. A high-titer positive anti-CCP at diagnosis is associated with a more aggressive, erosive disease course — more joint damage on X-ray, greater disability, and higher likelihood of needing biologic therapies (like TNF inhibitors or JAK inhibitors). Seronegative RA (negative RF and anti-CCP) tends to be milder and responds better to conventional DMARDs like methotrexate alone. However, disease activity should always be monitored clinically regardless of serology.
Can anti-CCP be positive before symptoms of arthritis appear?
Yes — this is one of the most important features of anti-CCP. Studies show anti-CCP can be detected in blood 5–10 years before the clinical onset of RA. This has led to research into "pre-RA" interventions. Incidental discovery of anti-CCP in a symptom-free individual does not mean treatment is needed immediately — but it warrants close follow-up with a rheumatologist for monitoring.