The diagnostic laboratory tests in rheumatic diseases (Chapter 7)

Laboratory tests are indeed helpful in the diagnosis and follow-up of rheumatic diseases. Alterations in laboratory parameters have been included among the classification or diagnostic criteria of several rheumatologic conditions and used as a means of monitoring disease activity and response to therapies. Apart from acute-phase reactants, which are unselectively increased across many inflammatory disorders, other laboratory findings may work as specific disease biomarkers, having therefore a diagnostic and prognostic role in clinical practice. Nevertheless, the request of laboratory tests should be dictated by a clear clinical indication in order to avoid misinterpretation and misdiagnosis. The aim of this chapter is to provide a comprehensive guidance on the indications, interpretation, and pitfalls of the laboratory tests currently available for the most relevant rheumatic diseases.