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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