Synonyms: Anti-thyroid peroxidase antibodies
Related tests: anti-thyroglobulin antibodies, FT3, FT4, TSH, thyroglobulin
Clinical significance
Anti-TPO antibodies are directed against the enzyme thyroid peroxidase, the main antigen of the microsomal fraction, which carries out iodination and the coupling of the thyroid residues MIT (monoiodotyrosine) and DIT (diiodotyrosine) to produce the active hormones thyroxine (T4) and triiodothyronine (T3). Anti-TPO antibodies are typically present in patients with autoimmune thyroid diseases, including most patients with chronic Hashimoto’s thyroiditis (>80%). They are also present in about 70% of patients with Graves’ disease. 14% of pregnant women have a positive anti-TPO titre.
Clinical indications
Autoimmune thyroid diseases (Hashimoto’s thyroiditis, idiopathic myxoedema, Graves’ disease).
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes.
Notes
In non-autoimmune thyroid diseases the frequency of anti-TPO is similar to that seen in healthy people. Anti-TPO antibodies have been found in 8-27% of the healthy population.