Imperial Collage Healthcare

Thyroid peroxidase (TPO) antibodies


Test Background
TPO is the immuno-active microsomal antigen. TPO antibodies are measured in patients with suspected hypothyroidism or hyperthyroidism. TPO is present in 50-80 % of Graves’ disease patients and in 80-95 % patients with Hashimoto’s thyroiditis (usually at high titres). 15 % of healthy females over the age of 40 also have these antibodies.


Clinical Indications

  • To identify an autoimmune cause for primary hypothyroidism
  • To identify the risk of progression to overt hypothyroidism in patients with borderline thyroid function tests (for individuals with TSH excess or mild thyroid failure, a positive TPO antibody indicates an approximate two-fold increase in risk of progression to overt hypothyroidism)
  • Prior to treatment with medication that may precipitate hypothyroidism
  • In pregnant women as a predictor of potential intrapartum hypothyroidism


Reference Range

<75 AU/mL


Sample Required
RST (rust top)


Sample Volume
5-10 mL (1 mL serum)


Turnaround Time
7 days


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