The antithyroid antibodies (AAT) are abnormal antibodies (autoantibodies) that attack the thyroid gland.

They appear mainly in case of autoimmune disease thyroid.

There are several types of AAT, which target different parts of the thyroid, including:

• anticorps anti-thyroperoxydase (anti-TPO)
• anti-thyroglobulin (anti-TG) antibody
• anti-TSH receptor antibodies
• anti-T3 and anti-T4 antibodies

The AAT are especially dosed in the event of symptoms of thyroid dysfunction, but also in the assessments ofinfertility (repeated miscarriages) or in the follow-up of pregnant women who have presented with thyroid disease. Their regular analysis is useful for monitoring thyroid autoimmune diseases.

The dosage of AAT is carried out by a blood sample venous, usually at the crease of the elbow. Results vary greatly from one analytical laboratory to another, and several measurements may be necessary. It is not necessary to be on an empty stomach before the sample.

The thyroid hormone assay (T3 and T4) can be performed at the same time.

The presence of AAT, especially in small amounts, is not always associated with symptoms.

When the levels are abnormally high (especially anti-TPO), it usually means that there is a dysfunction of the thyroid. Only the doctor can interpret the results and give you a diagnosis.

Some autoimmune thyroid diseases include:

• Hashimoto’s disease
• adolescent thyroiditis
• Graves’ disease
• postpartum thyroiditis (peak frequency 6 to 8 months after childbirth)

Pregnancy, certain cancers (thyroid), certain immune deficiencies can also be accompanied by an increase in AAT.