[Diagnostic value of autoantibodies against microsomal thyroid peroxidase (anti-TPO)]

With the identification of thyroid peroxidase (TPO) as the main antigen of the thyroid microsomal fraction, the development of a sensitive and specific assay for detection of these antibodies became possible. The diagnostic value of the anti-TPO assay was evaluated in patients with different types of thyroid disease and in controls. 65% of patients with thyroiditis had elevated anti-TPO values. The frequency of elevated anti-TPO levels in patients with active autoimmune thyroiditis was 90% (clinical diagnosis Hashimoto thyroiditis) compared to 64% in patients with overt hyperthyroidism (clinical diagnosis Graves' disease). None of the controls or the patient with non-thyroidal illness showed elevated anti-TPO levels.