Anti-TG

Anti-TG are antibodies to thyroglobulin, a thyroid protein from which its hormones are made. The test is performed when autoimmune thyroid disease is suspected, most often alongside anti-TPO, and when monitoring patients after thyroid cancer treatment, alongside thyroglobulin.

Who is this test for

• people whose TSH or fT4 suggest an underactive or overactive thyroid when a doctor wants to check whether the cause is autoimmune;
• people with an enlarged thyroid (goitre) or ultrasound findings suggesting thyroid inflammation;
• people with suspected Hashimoto’s thyroiditis or Graves’ disease, most often together with anti-TPO;
• people treated for differentiated thyroid cancer whenever thyroglobulin is measured.

What anti-TG antibodies are and what they show

Thyroglobulin is produced in the thyroid and serves as a “store” for making T4 and T3 hormones. In autoimmune diseases, the immune system mistakenly recognises parts of its own thyroid as foreign and produces antibodies, including anti-TG.

Anti-TG is not the same as thyroglobulin (TG). Thyroglobulin is a protein monitored as a tumour marker after thyroid cancer surgery, while anti-TG are antibodies directed against it. These are two different tests.

Save with a panel

Test Anti-TG is also included in this panel.

Complete thyroid panelTSH, T3, T4, fT3, fT4 and 2Price of individual tests: 102.00€92.00€Details ›

Preparation and sample

Anti-TG is measured in venous blood. Fasting is not required and blood may be taken at any time of day. Do not stop thyroid treatment yourself. If you take biotin (e.g. hair and nail supplements), mention this at blood collection.

How results are interpreted

The reference value depends on the method and is printed on your report. A doctor interprets it alongside TSH, thyroid hormones, anti-TPO and ultrasound.

High anti-TG in autoimmune thyroid disease

Elevated antibodies most often accompany Hashimoto’s thyroiditis (chronic lymphocytic thyroiditis), the most common cause of an underactive thyroid. They may also be elevated in Graves’ disease and some other autoimmune diseases. Anti-TPO is more sensitive for Hashimoto’s thyroiditis, so anti-TG is usually measured alongside it rather than instead.

High anti-TG does not always mean disease. Antibodies are also found in some healthy people, more often women and older people. If thyroid function is normal, a doctor usually recommends periodic TSH checks because these people have an increasing likelihood of developing an underactive thyroid over time.

Antibody levels do not show disease severity or determine treatment. Abnormal thyroid function is treated, for example with hormone replacement when it is reduced. There is no medicine specifically lowering antibodies and thereby changing the course of disease; most patients with Hashimoto’s thyroiditis do not need regular repeat antibody tests: TSH is monitored.

Anti-TG after thyroid cancer treatment

After differentiated thyroid cancer surgery, thyroglobulin is used to monitor disease. Anti-TG antibodies can interfere with its measurement and cause falsely low thyroglobulin, so antibodies are measured with every thyroglobulin test. If present, their level over time becomes a surrogate marker: a gradual fall is favourable, while a rise may prompt further investigations decided by a doctor. Read more about the disease itself in the article on early symptoms of thyroid cancer.

How to arrange testing

You can come for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the Contactpage). Prices for all tests and panels are listed in the service price list. If thyroid function is also being assessed, the Complete thyroid panel, containing anti-TG together with anti-TPO, TSH, T3, T4, fT3 and fT4, is more practical.

Frequently asked questions

What does high anti-TG mean?

It most often suggests autoimmune thyroid disease, particularly Hashimoto’s thyroiditis. It is not a diagnosis by itself: a doctor interprets it alongside TSH, fT4 and anti-TPO, and with normal thyroid function, elevated antibodies usually mean only that periodic checks are needed.

Should anti-TG be checked every year?

Usually not in Hashimoto’s thyroiditis. Thyroid function is monitored, primarily TSH, at intervals set by a doctor. Anti-TG is regularly measured after thyroid cancer treatment alongside thyroglobulin.

Can antibodies be lowered through diet or supplements?

In some studies, selenium reduced antibody levels, but this has not been shown to change disease course or thyroid function. Discuss supplements, particularly iodine and selenium, with your doctor before starting them.

Can anti-TG and anti-TPO differ?

Yes. Some people have only one of these antibodies elevated, while others have both. They are therefore often measured together when investigating autoimmune thyroid disease.