Investigations in rheumatology

Laboratory investigations play an important role in the diagnosis of rheumatic disorders but many tests are of limited specificity. It is therefore important to select tests in the light of careful clinical assessment rather than blindly sending off a battery of requests, as the results may be confusing. We review the frequency of autoantibodies in different disorders and their value for diagnosis and, in some cases, for prognosis and monitoring. We also review the relative merits and disadvantages of plain radiographs, ultrasound, isotope, CT and MR imaging for different types of musculoskeletal problem. Finally we describe the typical imaging characteristics of degenerative and inflammatory disorders including rheumatoid arthritis and seronegative spondyloarthropathies in the peripheral joints and spine.