The clinical use of thyroid autoantibodies

Thyroid antibody measurements can be useful in managing patients with Graves’ disease, autoimmune thyroiditis, and the polyglandular failure syndromes. Some thyroid autoantibodies appear to be responsible for the disease process, others to be a response to thyroid cell damage. Oligoclonal antibodies appear to be causal, polyclonal antibodies to be a response to thyroid cell injury. Many thyroid antibodies are found in normal people but are clinically significant only when of high affinity and in high titer. The TSH receptor antibody is not found in normal subjects, suggesting an important role for this molecule in the etiology of Graves’ disease. The production of “primary” autoantibodies like the TSH receptor antibody may represent the escape of a “forbidden clone” from the normal suppressor mechanisms. The incomplete concordance of Graves’ disease in identical twins suggests that both genetic and environmental factors play a role in this disease process. The practical aspects of autoantibody measurement in general and their interpretation are reviewed in some detail.