TPO / MAK (Autoantibodies against Thyroid Peroxidase)

TPO or MAK antibodies target the enzyme thyroid peroxidase, which is needed in the thyroid gland for the production of thyroid hormones. If such antibodies are formed, the immune system attacks the thyroid gland – an indication of an autoimmune disease.

They most commonly occur in Hashimoto's thyroiditis or Graves' disease. A positive test thus indicates such an autoimmune reaction, even if the level of antibodies does not always directly correlate with the severity of the disease.