Cyclic Citrullinated Peptide Antibody, IgG and IgA

19 Units or less:           Negative
20-39 Units:                  Weak positive
40-59 Units:                  Moderate positive
60 Units or greater:     Strong positive

A positive result for cyclic citrullinated peptide (CCP) antibodies in conjunction with consistent clinical features may be suggestive of rheumatoid arthritis (RA). Anti-CCP, IgG/IgA antibodies are present in about 66-74 percent of RA patients and have specificities of 96-99 percent. Detection of IgA antibodies in addition to the usual IgG antibodies enhances the sensitivity due to some RA patient shaving IgA antibodies to CCP in the absence of IgG. These autoantibodies may be present in the preclinical phase of disease, are associated with future RA development, and may predict radiographic joint destruction. Patients with weak positive results should be monitored and testing repeated.