Anti-CCP

In rheumatoid arthritis the immune system turns against your own joints. One of the first steps is that proteins in the body undergo a small chemical change, citrullination, after which the immune system sees them as foreign and makes antibodies against them. Anti-CCP measures those antibodies, against a laboratory-built version of such modified proteins. Those antibodies are remarkably faithful to one disease. Where the older rheumatoid factor also occurs with infections, other autoimmune diseases and healthy older people, anti-CCP belongs almost exclusively to rheumatoid arthritis. A positive result therefore makes that diagnosis likely, and the antibodies are often present years before a joint hurts. Conversely, about a third of people with rheumatoid arthritis have no anti-CCP, so negative does not rule the disease out. Your report shows anti-CCP as a number with a limit: below 7 the result is called negative, above 10 positive, and in between equivocal. The unit differs per lab and the numbers cannot be swapped between labs; the higher above the limit, the more certain the result.

Rheumatoid arthritis is a disease in which starting treatment early makes the difference between joints that stay intact and joints that deform. The first months after the first complaints are the window in which the disease can still be tamed. Anti-CCP is the number that helps recognise that window: in someone with painful, swollen joints, stiff in the morning and on both sides, a positive result makes the diagnosis likely and the step to a rheumatologist urgent. That is also the reason not to have it measured casually. Without joint complaints a positive result says there is an increased chance of rheumatoid arthritis in the coming years, not that it is there, and there is no treatment that prevents the disease at that point. Anyone who tests positive without complaints is mainly left with worry. That is why this is a test for complaints, and not part of a health check. What you do control comes beforehand. Smoking is the strongest lifestyle factor behind these antibodies: smoke sets in motion in the lungs exactly the citrullination the immune system reacts to, and smokers more often get the anti-CCP-positive, more stubborn form of the disease. Inflamed gums and excess weight contribute too. For anyone with a parent or sibling with rheumatoid arthritis, not smoking and healthy gums are the best prevention there is.

A positive anti-CCP is almost always rheumatoid arthritis or its early stage; the higher the value, the more certain. With joint complaints that is a reason to see a rheumatologist quickly, because early treatment protects the joints. Without complaints it means an increased chance in the coming years, and then stopping smoking, healthy gums, a healthy weight and staying alert to swollen joints are what you can do. Rarely a positive result occurs with another autoimmune disease, such as the arthritis of psoriasis or Sjögren's syndrome. A negative anti-CCP does not rule rheumatoid arthritis out: about a third of people with the disease do not have the antibody, and in them the diagnosis is made on the joints themselves, rheumatoid factor and the inflammation values. A negative result with complaints is therefore not an endpoint. An equivocal result, between 7 and 10, is repeated after a few months, because the antibody usually keeps rising as the disease develops. Set anti-CCP beside rheumatoid factor, which is more sensitive but less specific: both positive is the strongest pattern. CRP and ESR show whether there is inflammation at that moment. And the most important thing is not on the report: which joints, for how long, and how stiff in the morning.