Thyroid peroxidase (TPO) is a large (105 kDa) membranebound glycoprotein of the thyroid gland. It is the major enzyme involved in multiple steps of thyroid hormone synthesis. TPO is one of three major thyroid autoantigens (besides thyroglobulin (Tg) and the TSH-receptor). The presence of autoantibodies to TPO and Tg today is an established tool for diagnosing chronic autoimmune thyroiditis as well as for the differential diagnosis of hypothyroidism including its subclinical or latent type.
Autoantibodies to Tg and TPO are important for ruling out autoimmune thyroid diseases, as over 98% of thyroiditis patients display autoantibodies to either one or both of these antigens.
Anti-TPO antibodies are found in 71-97% of patients with Graves disease and 91-99% of patients with Hashimoto’s thyroiditis. Negative tests for anti-Tg and anti-TPO can virtually exclude an autoimmune thyroiditis. These autoantibodies do also occur in patients with adenocarcinoma of the thyroid or hyperthyroidism and are found in healthy individuals at low levels.
A follow-up to a 20-year community study in England concluded that a primary risk factor for future autoimmune thyroid dysfunction was a positive thyroid autoantibody test
Method:
Immunoenzymatic method for the quantitative determination of IgG class antibodies against Thyroid Peroxidase (TPO) in human serum, using a disposable device applied on the Chorus and Chorus TRIO instruments. The test is based on the ELISA principle (Enzyme Linked ImmunoSorbent Assay) which uses the reaction between the antibodies present in the tested sample and the immobilized antigen bound to solid phases.The immunoglobulins bind to the antigen through incubation with diluted human serum.The disposable devices contain all the reagents to perform the test when applied on the Chorus instruments. The results are expressed in International Units (IU/ml) calculated in reference to WHO 66/387.
