Special Precautions/Comments:

Additional Information:

TPO is a potential autoantigen. Elevated serum titres of antibodies to TPO are found in several forms of thyroiditis caused by autoimmunity. TPO was identified as the causative antigen in 1985 when studies demonstrated that human antisera reacting to “microsomal antigen” precipitated TPO prepared from Graves’ disease thyroid tissue.

Clinically the two terms anti TPO and microsomal antibody can be used synonymously; there are differences, however, with regard to the test methods. High anti TPO titres are found in up to 90 % of patients with chronic Hashimoto’s thyroiditis. In Graves’ disease, 70 % of the patients have an elevated titer. Although the sensitivity of the procedure can be increased by simultaneously determining other thyroid antibodies (anti Tg, TSH receptor antibody – TRAb), a negative finding does not rule out the possibility of an autoimmune disease.

The magnitude of the antibody titre does not correlate with the clinical activity of the disease. Initially elevated titres can become negative after lengthy periods of illness or during remission. If antibodies reappear following remission, then a relapse is probable.