Diagnostic testing and interpretation of tests for autoimmunity.

Laboratory testing is of great value when evaluating a patient with a suspected autoimmune disease. The results can confirm a diagnosis, estimate disease severity, aid in assessing prognosis and are useful for following disease activity. Components of the laboratory examination include a complete blood count with differential, a comprehensive metabolic panel, measurement of inflammatory markers and autoantibodies, and flow cytometry. This chapter discusses these components and includes a discussion about organ-specific immunologic diseases for which immunologic laboratory testing is used. Comprehensive laboratory evaluation of a suspected autoimmune illness in conjunction with a thorough clinical evaluation provides a better understanding of a patient's immunologic disease.