Anti-tpo antibody

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Antibodies against thyroidal peroxidase; Antibodies against thyroperoxidase; Antibodies against TPO; MAK; Microsomal antibodies; TPO antibody

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"MAK" is the acronym for"microsomal antibodies", antibodies against thyroid microsomes. However, these antibodies are not only directed against microsomes but especially against the enzyme TPO (thyroid peroxidase). Therefore, the microsomal antibodies are also called"TPO antibodies".

Note: TPO is a key enzyme in the biosynthesis of thyroid hormones. It is responsible for the iodination of thyroglobulin and for the coupling of two dityrosines.

General information
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Increased values:

  • Highly elevated levels of the autoantibodies MAK (TPO-Ak) and TAK in serum are mainly found in chronic lymphocytic thyroiditis (Hashimoto) and postpartum thyroiditis. In Hashimoto's thyroiditis, lymphocytes and plasma cells migrate into the thyroid gland and destroy the thyroid tissue. After an initial overactive state, the thyroid gland becomes permanently underactive (hypothyroidism). MAK/TPO-Ak are 60-90% positive.
  • Primary myxedema: MAK/TPO-Ak are 40-70% positive.
  • Autoimmune thyroiditis (Graves' disease): MAK/TPO-Abs are 60-70% positive.
  • Postpartum thyroiditis: MAK/TPO-AK are 50-70% positive.

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Test material: Serum

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Normal values (The reference values as well as the determined values may vary considerably from laboratory to laboratory).

negative: < 35 U/ml (no increased antibodies)

positive: > 35 U/ml (increased antibodies)

In healthy people the TPO antibodies are < 100 U/ml, which means they are negative. Clearly positive TPO-antibodies > 200 U/ml are an indication of chronic lymphocytic thyroiditis (Hashimoto ). They are positive in 90% of cases of this disease.

For the course of Hashimoto's thyroiditis, the level of TPO antibodies in the blood has no relevance to the course of the disease. The level of TPO-antibodies does not allow a statement about the severity of the disease.

Note: After a normal pregnancy, increased TPO-AK occurs in 10% of women.

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  1. Classen M et al (2004) In: Classen M et al (Hrsg) Endocrine disorders. Urban § Fischer publishing house Munich, Jena p.323
  2. Böhm BO (2018) Thyroid hormones. In: Neumeister B et al. (Eds) Clinical guide to laboratory diagnostics. Elsevier GmbH S. 416
  3. Hennessey VY (2015) Diagnosis and Management of Subclinical Hypothyroidism in Elderly Adults: A Review of the Literature. Journal of the American Geriatrics Society 63: 1663-1673.


Last updated on: 29.10.2020