The Thyroid Antibodies test measures the levels of two key antibodies—Thyroid Peroxidase Antibodies (TPOAb) and Thyroglobulin Antibodies (TgAb). These antibodies are markers of autoimmune thyroid disorders. Elevated levels can indicate conditions such as Hashimoto's thyroiditis or Graves' disease, and the test is used to diagnose and monitor these thyroid conditions.