Citrulline Antibody

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What is citrulline antibody?

Citrulline antibody is an immune protein (antibody) that binds to a non-standard amino acid (citrulline) that is formed by removing amino groups from the natural amino acid, arginine. Citrulline antibodies are measured with a blood test that is analyzed in laboratories.

Research suggests that in the joints of patients with rheumatoid arthritis, proteins may be changed to citrulline as part of the process that leads to inflammation of the rheumatoid joint. Citrulline antibody has also been referred to as anti-citrulline antibody, anti-cyclic citrullinated peptide antibody, and anti-CCP.

For what is citrulline antibody used?

Citrulline antibody is present in the blood of 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 substance detected by 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 citrulline antibody test then can be used by doctors to encourage them to proceed with the optimal treatments directed toward rheumatoid arthritis. Research has found that the presence of citrulline antibodies has also been associated with a greater tendency toward more destructive forms of rheumatoid arthritis.

How specific is the citrulline antibody blood test for rheumatoid arthritis?

When the citrulline antibody is found in a patient's blood, there is a 90%-95% likelihood that the patient has rheumatoid arthritis.

Medically reviewed by Kirkwood Johnston, MD; American Board of Internal Medicine with subspecialty in Rheumatology


"Clinically useful biologic markers in the diagnosis and assessment of outcome in rheumatoid arthritis"

Medically Reviewed by a Doctor on 3/26/2014