Antibodies to thyroperoxidase (Anti TPO)

Thyroid peroxidase (TPO) Is an enzyme involved in the synthesis of thyroid hormones - triiodothyronine (T3) and thyroxine (T4).

Thyroid peroxidase (TPO) is a glycosylated transmembrane protein that is localized in the apical (upper) part of follicular cells and is expressed only in thyrocytes.

It is one of the most important antigens of the thyroid gland, to which it also belongs Thyroglobulin (The main component of the colloid) and TSH receptor (Located on the basement membrane of thyroid cells).

The thyroid gland is the target organ for many autoimmune diseases, for example: Graves' disease, which is accompanied by thyrotoxicosis, Hashimoto's thyroiditis, which also causes hypothyroidism. A characteristic feature of these diseases is the loss of immune tolerance to thyroid peroxidase, and Antibodies to thyroid peroxidase (TPO) Occurrence, which is a specific sign of these diseases.

Determining the level of anti-thyroperidase antibodies (anti-TPO) is the most sensitive test for autoimmune thyroid disease. Elevated levels of anti-TPO are found in 90-95% of patients with autoimmune thyroiditis (eg, chronic Hashimoto's thyroiditis) and in 80% of patients with Graves' disease.

The sensitivity of this diagnostic test may be increased by the simultaneous detection of other thyroid antibodies (thyroglobulin, anti-TSH receptor antibodies (TRAb). The level of these antibodies is not related to the severity of the disease. Recurring again after remission, this indicates an probable recurrence of the disease.

Patients with subclinical hypothyroidism have a higher risk of developing pronounced hypothyroidism when exposed to anti-TPO.

Determining the level of antibodies to thyroid peroxidase during pregnancy (anti-TPO) may contribute to an increased risk of postpartum thyroiditis, which develops in 5-10% of postpartum women and is associated with destructive thyrotoxicosis and transient hypothyroidism. In pregnant women with increased rates of anti-TPO, this risk is about 50%.

Before taking amiodarone, interferon, lithium preparations, it is advisable to determine the level of anti-TPO and Anti TG to assess the risk of developing thyroid pathology.

Absence of anti-TPO and anti-TG does not rule out the presence of autoimmune thyroiditis mainly in a very small number of patients under 20 years of age.

When should we test for antibodies against thyroperoxidase?

• Diagnosis and detection of autoimmune diseases of the thyroid gland;
• Screening in the first trimester of pregnancy, to identify the risk of developing thyroid dysfunction during pregnancy and postpartum thyroiditis;
• Identify risk factors for the development of neonatal hypothyroidism;
• Identify risk factors for termination of pregnancy;
• Assess the risk of thyroid pathology in patients prior to the appointment of amiodarone, interferon, and lithium supplements.

Anti-TPO antibodies may also be positive in 3% of individuals who do not have obvious symptoms of thyroid damage (especially in older women).

How to prepare for the test?

The test should be performed on an empty stomach.

Research material

Venous blood

Possible interpretation of the results

Elevated levels of anti-thyroperidase antibodies (anti-TPO):

• Autoimmune thyroiditis (Hashimoto's thyroiditis);
• Diffuse toxic goiter (Graves' disease);
• Nodular toxic goiter;
• Subacute thyroiditis;
• Postpartum dysfunction of the thyroid gland.
• Non-thyroid autoimmune diseases (Schengen syndrome, lupus erythematosus, rheumatoid arthritis).

Resources

https://spravochnik.synevo.ua/ru/thyrioidnaia/peroxidasa-shitovidka-antitela.html