Citrulline antibody is present in most patients with rheumatoid  arthritis. It is used in the diagnosis of rheumatoid arthritis when evaluating patients with unexplained joint inflammation. A test for citrulline antibodies is most helpful in looking for the cause of previously undiagnosed inflammatory arthritis when the traditional blood test for rheumatoid arthritis, rheumatoid factor, is not present. Citrulline antibodies have been felt to represent the earlier stages of rheumatoid arthritis in this setting.
The anti-CCP test should be useful in identifying patients with early seronegative polyarthritis as individuals with rheumatoid arthritis when the test is positive.

Potential false positives in some tested cases:

1. Parvoviral Arthropathy, 5%of cases
2. SLE, 2.5% of cases
3. Early Synovitis
4. Hepatitis C
5. Seronegative Inflammatory Arthropathy
6. Polymyalgia Rheumatica
7. Sarcoidosis
8. Spondyloarthropathy 0/19
9. Ankylosing Spondylitis
10. Psoriatic Arthritis
11. Reiter's Syndrome
12. Inflammatory Bowel Disease with Arthritis
13. Undifferentiated Spondyloarthropathy
14. Fibromyalgia
15. Remitting Seronegative Symmetrical Synovitis with Pitting Edema