Laboratory testing for the rheumatic diseases can allow for rapid diagnosis and appropriate management, while false-positive tests can lead to inappropriate management and unnecessary concern for the patient. An evaluation of laboratory testing for rheumatic illnesses is discussed, including the well-known acute phase proteins, the use of ANA in screening, and the newer antibodies which may potentially allow for an earlier diagnosis. A thorough history and examination are arguably the best screening tests. Clinicians should be judicious in their use of laboratory testing, and should only do so in an attempt to further refine the diagnosis.
* While laboratory testing can help with the diagnosis of rheumatic disease, overreliance on a lab result may lead the clinician to an incorrect diagnosis.
* Antinuclear antibodies are present in a number of connective tissue diseases; while nearly all patients with lupus are ANA-positive, the high number of false positives limits its utility as a screening test.
* New tests, such as the cyclic citrullinated protein antibody, may improve early identification of patients with rheumatoid arthritis, particularly those with a prognosis for a more aggressive disease.