Which antibody is most specific for Hashimoto's thyroiditis?

• A. Anti-thyroglobulin antibodies
• B. TSH receptor antibodies
• C. ANA antibodies
• D. Anti-TPO antibodies

Answer: (D)

Anti-TPO antibodies are the antibody most specific for Hashimoto's thyroiditis. Thyroid peroxidase is essential for thyroid hormone synthesis, and antibodies against it (anti-TPO) appear in the vast majority of Hashimoto's cases. This makes anti-TPO a highly characteristic marker for autoimmune thyroiditis. Anti-thyroglobulin antibodies can be seen in various thyroid diseases and are less specific. TSH receptor antibodies are classically linked to Graves disease (they stimulate the receptor) and are not as specific for Hashimoto's. ANA is a nonspecific autoimmune marker not diagnostic for thyroid disease.