Antithyroid antibody: An antibody directed against the thyroid gland, a gland which produces thyroid hormones (such as, for example, thyroxine and triiodothyronine). Antithyroid antibodies can be associated with inflammation of the thyroid gland and affect its function. Antithyroglobulin and antimicrosomal antibodies are examples of antithyroid antibodies.
Testing for antithyroid antibodies in the blood is useful in the diagnosis of some thyroid and other disorders. Conditions in which there may be antithyroglobulin antibodies include: Hashimoto thyroiditis (an autoimmune thyroid disease), Graves disease (overactivity of the thyroid), hypothyroidism (underactivity of the thyroid), thyroid cancer, lupus, rheumatoid arthritis, autoimmune hemolytic anemia and Sjogren syndrome.