[Immune diagnostics in rheumatology]

Laboratory diagnostics play a fundamental role in rheumatology but must always be interpreted in the context of symptoms and clinical signs. Laboratory tests have a variety of purposes, such as confirmation or negation of a diagnosis, differential diagnosis, evaluation of activity and prognosis, involvement of organs and drug side effects. Markers of inflammation and specific autoantibodies are the most important laboratory parameters in rheumatology. Thus, with the suspicion of rheumatoid arthritis the analysis of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), the rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP or ACPA) should be performed as the first line tests. Only a few antibody titers are suitable for monitoring of disease activity. Some autoantibodies exhibit such a high diagnostic value that the antibodies are included in the classification criteria or in the definition of a disease entity.