Thyroid autoantibodies

The prevalence of and predictive value of testing for thyroid autoantibody have been studied in a wide variety of conditions. Table 7 summarizes the authors' view on the current clinical indications for the use of these tests. Anti-TPO antibody testing by immunoassay has replaced anti-Tg and antimicrosomal antibody testing in routine practice because of its improved sensitivity and specificity and should be easily available to all physicians who manage thyroid disease. Currently, the only clear indication for anti-Tg testing is in patients in whom serial Tg measurements are planned as follow-up for differentiated thyroid cancer. The use of anti-TSH receptor antibody testing in routine clinical practice remains controversial. Although there are specific indications in which accurate anti-TSH receptor antibody testing might influence management, particularly in pregnancy and the puerperium, the lack of routine availability of the test and the fact that a combination of anti-TPO antibody testing, clinical information, and isotope scanning can often serve as a reasonable substitute means that many clinicians do not perform anti-TSH receptor antibody testing. Whether the advent of novel highly automated binding and bioassays with improved sensitivity will alter the balance of test usage in these situations remains to be seen. Antibodies to eye muscle proteins and the NIS are areas of active research interest and further study may result in the definition of a clinical indication for these additional tests.