Newcastle Laboratories

Anti-thyroid peroxidase, serum

Clinical Background:

Thyroid peroxidase (TPO) is a membrane bound glycosylated haem-containing protein found in the apical membrane of the thyroid follicular cells. TPO, the major component of a large protein known as ...

Thyroid peroxidase (TPO) is a membrane bound glycosylated haem-containing protein found in the apical membrane of the thyroid follicular cells. TPO, the major component of a large protein known as thyroid microsomal antigen, catalyses the iodination of the tyrosyl groups in thyroglobulin resulting in the synthesis of thyroid hormones, T3 and T4. Autoimmune thyroid disease is characterised by the presence of autoantibodies against TPO. Anti-TPO antibodies activate complement and are thought to be significantly involved in thyroid dysfunction and the pathogenesis of hypothyroidism.
The measurement of autoantibodies against thyroid peroxidise is useful in identifying patients with autoimmune thyroid disease. Levels of anti-TPO antibodies are increased in greater than 90% of patients with active autoimmune thyroiditis. In patients with autoimmune thyroid disease, anti-TPO antibodies are present in nearly all patients with Hashimoto’s thyroiditis and in greater than 70% of patients with Grave’s disease. Anti-TPO antibodies are also present in patients with atrophic thyroiditis and primary myxoedema.

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Test Details

  • Discipline:

    Biochemistry

    Biochemistry

  • Specimen Container Adult:

    Serum - SST

    Serum - SST

  • Specimen Container Paediatric:

    Serum-Plain tube

    Serum-Plain tube

  • Minimum Volume Adult:

    1 mL blood

    1 mL blood

  • Minimum Volume Paediatric:

    0.5 mL blood

    0.5 mL blood

  • Special Requirement:

    None noted.

    None noted.

  • Sample Stability:

    Unseparated: unknown
    Separated: 3 days at 4-8°C, 1 month at -20°C

    Unseparated: unknown
    Separated: 3 days at 4-8°C, 1 month at -20°C

  • Transport Requirements:

    Ambient

    Ambient

  • Interpretation:

    Slightly elevated anti-TPO antibodies can be detected in about 10% healthy individuals with normal thyroid function: the clinical significance of this has not been determined. The measurement of an...

    Slightly elevated anti-TPO antibodies can be detected in about 10% healthy individuals with normal thyroid function: the clinical significance of this has not been determined. The measurement of anti-TPO is therefore of little clinical value in the presence of normal thyroid function tests, except in the investigation of patients with other autoimmune diseases in whom it may be important to detect thyroid involvement. In patients with borderline TSH values but normal free T4 levels, indicating subclinical hypothyroidism, raised anti-TPO antibodies is associated with an increased risk of progression to overt hypothyroidism. Anti-TPO antibodies are increased in women with postpartum thyroiditis, this condition occurring in 5 – 9% of postpartum women. Although postpartum thyroiditis is associated with anti-TPO antibodies, 50% of anti-TPO positive women do not develop thyroid dysfunction.

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  • Reference Ranges:

    <34 kU/L

    <34 kU/L

  • Factors Affecting Result:

    Gross haemolysis, icterus or lipaemia may interfere.

    Gross haemolysis, icterus or lipaemia may interfere.

  • Other Info:

    Plasma- Lithium Heparin also acceptable

    Plasma- Lithium Heparin also acceptable

  • Routine Contact Name:

    Duty Biochemist

  • Routine Telephone:

    Freeman: 0191 244 8889

    RVI: 0191 282 9719

    Freeman: 0191 244 8889

    RVI: 0191 282 9719

  • Routine Email:

    - For external users: TNU-Tr.duty.biochemist@nhs.net

    - For Trust users: DutyBiochemist@nuth.nhs.uk

Availability:

Available during full access hours
Assayed daily
Site of analysis: RVI

Turn Around:

Within 2 full access days

Send To:

Department of Blood Sciences

Level 3
Leazes Wing
Royal Victoria Infirmary
Queen Victoria Road
Newcastle upon Tyne
NE1 4LP

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