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Thyroid peroxidase (TPO) antibodies

General information

TPO is the immuno-active microsomal antigen

Specimen transport: At room temperature

Repeat frequency: significant change of clinical symptoms

Special precautions: None

Laboratory information

Normal reference range: 0-59 kU/L

Volume and sample type: 7ml clotted blood

Method: FEIA (Fluoroenzyme Immunoassay)

Turnaround time (calendar days from sample receipt to authorised result): Median: 2

Clinical information

Indications for the test:

  • 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.

Factors affecting the test: Present in high titre in 95% of patients with Hashimoto's thyroiditis, some patients with Grave's disease and primary myxoedema. Anti-TPO are also seen in 5-15% of normals but at low titre.


ICE reference: Thyroid peroxidase Antibodies


(Last updated August 22nd 2018)