Insight into your anti-TG level.
Anti-TG are antibodies against thyroglobulin, the protein the thyroid itself makes as a building block for thyroid hormone. The result is usually read together with anti-TPO and your thyroid function.
Also known as: Anti-Tg, TgAb, Thyroglobulin antibodies
Personal assessment by our BIG-registered doctors
By the Bloodworks editorial team
How Bloodworks works
Order online
Choose your package and preferred location
Receive your lab form
Within 24 hours by email, with appointment planner
Schedule your blood draw
Or choose a walk-in location
Blood draw
Takes just a few minutes
Receive your report
Securely, typically within 2 working days from our physicians
Background
What are anti-TG antibodies?
Thyroglobulin, or Tg for short, is a large protein the thyroid produces itself. It serves as a building block and as a storage form for thyroid hormone: the hormones T4 and T3 are formed within this protein and kept there until the body needs them. In some people the immune system makes antibodies against this own protein. These are the anti-TG antibodies, also called Tg antibodies or TgAb. Their presence shows that the immune system is directed at thyroid tissue. That fits with an autoimmune thyroid condition, such as Hashimoto's disease. Anti-TG is therefore almost always read alongside anti-TPO. Anti-TPO occurs more often and is usually measured first in practice; anti-TG mainly adds information in people whose anti-TPO is not detectable.
An antibody measures the possible cause of a thyroid problem, not how the thyroid is working. That function is measured with TSH and Free T4: TSH is the signalling hormone from the pituitary gland, Free T4 the hormone the thyroid produces. A detectable anti-TG is therefore not a diagnosis in itself. Antibodies also occur in people with a normally functioning thyroid and no symptoms, more often in women and at older ages. In addition, how high the value is says nothing about the severity of any condition or about your symptoms, which is why anti-TG is usually not repeated to follow a course over time. There is a second, quite different reason why anti-TG is requested in regular care. In follow-up after thyroid cancer, thyroglobulin itself is measured in the blood as an indicator of remaining thyroid tissue. Anti-TG antibodies can interfere with that measurement, so they are routinely measured alongside it in that setting. Such monitoring runs through the treating specialist and is separate from the test you order here.
In brief
Antibody
Directed against thyroglobulin, a protein of the thyroid itself
Alongside anti-TPO
Anti-TPO occurs more often and is usually measured first
Not a function test
Function is measured with TSH and Free T4
No measure of severity
The level says nothing about how severe symptoms are
Common reasons to test
When can insight into your Anti-TG be valuable?
Below are some situations in which measuring Anti-TG can provide insight.
As an addition to an anti-TPO test
Anti-TPO is usually the first antibody measured. If it is not detectable while the question of an autoimmune cause remains, anti-TG can fill in the picture.
Context for an abnormal thyroid value
If your TSH or Free T4 is abnormal, thyroid antibodies show whether the immune system plays a role, as in Hashimoto's disease.
With thyroid conditions in the family
Autoimmune thyroid conditions run in families. With a family history, thyroid antibodies give additional insight.
With another autoimmune condition
Autoimmune conditions more often occur together. Those who already have one sometimes include thyroid antibodies in their testing.
Before and during a wish to conceive
Thyroid antibodies play a role in questions around fertility and pregnancy. A test may form part of preconception checks.
With a borderline value you want to interpret
With a slightly abnormal TSH, thyroid antibodies help to place the result and to judge whether follow-up is worthwhile.
Alongside a thyroglobulin measurement
In follow-up after thyroid cancer, thyroglobulin is measured. Anti-TG is routinely measured with it, because the antibodies can interfere with that measurement. Such monitoring runs through your treating specialist.
What your result means
Anti-TG detectable or undetectable: what does your result mean?
Anti-TG is measured in kU/L, sometimes expressed as IU/mL. The laboratory states the reference values that apply there alongside your result; those are leading. Important: an antibody measures the possible cause and not how your thyroid is working. That function is measured with TSH and Free T4. An anti-TG result can therefore only be interpreted together with your thyroid function and your personal situation.
A low or undetectable value
If the antibodies are undetectable or barely detectable, that makes an autoimmune thyroid condition less likely. It cannot be ruled out entirely: a share of people with an autoimmune thyroid condition have no detectable antibodies. If there are symptoms, or if your thyroid function is abnormal, that function remains leading for the next step.
A value within the reference range
An anti-TG within the laboratory's reference values is usually reported as negative. That gives a reassuring picture for this marker. In itself it says nothing about how your thyroid is working, for which our doctor looks at TSH and Free T4.
An elevated value
An elevated anti-TG means antibodies against thyroglobulin are detectable. That fits with an autoimmune thyroid condition. It is not a diagnosis in itself: a detectable value also occurs in people with a normally functioning thyroid and no symptoms. How high the value is says nothing about severity, which is why the test is usually not repeated. Our doctor assesses the result together with your thyroid function and any anti-TPO, and explains whether follow-up or periodic monitoring is customary.
How we interpret your result
Our doctors interpret your anti-TG against the laboratory's reference values, your thyroid function and your personal context, such as symptoms, family history and medication use.
Related tests
Often combined with Anti-TG.
A single marker gives one perspective. For a broader picture you can combine Anti-TG with a theme package or related markers.
+ €29 blood draw fee per orderFree from €225
Frequently asked questions
Everything you want to know
What are anti-TG antibodies?
Anti-TG, also called Tg antibodies or TgAb, are antibodies the immune system makes against thyroglobulin. That is a protein the thyroid produces itself and uses as a building block and storage form for thyroid hormone. Detectable anti-TG shows that the immune system is directed at thyroid tissue. That fits with an autoimmune thyroid condition, such as Hashimoto's disease.
What is the difference between anti-TG and anti-TPO?
Anti-TPO is directed against thyroid peroxidase, the enzyme needed to produce thyroid hormone. Anti-TG is directed against thyroglobulin, the protein in which the thyroid forms and stores hormone. Both belong to the same question, namely whether the immune system is involved. Anti-TPO occurs more often and is therefore usually measured first. Anti-TG mainly adds information when anti-TPO is not detectable.
Does a detectable anti-TG mean I have a thyroid condition?
No. A detectable value fits with an autoimmune thyroid condition, but is not a diagnosis in itself. Antibodies also occur in people with a normally functioning thyroid and no symptoms. An antibody measures the possible cause, not how the thyroid is working. That function is measured with TSH and Free T4. Our doctor explains what your result means in your situation.
Does the level of the anti-TG value say anything about severity?
No. A strongly elevated value does not mean you have more symptoms or that a condition will follow a heavier course. The level of the antibodies does not track severity. This is why anti-TG is usually not repeated to follow a course over time. What people do instead is have their thyroid function checked periodically with TSH and Free T4.
Do I need to fast for an anti-TG test?
No, you do not need to fast for anti-TG. You can have blood drawn at any time of day. If you combine the test with glucose or cholesterol, for example, the fasting instructions do apply to those tests.
Why is anti-TG used in follow-up after thyroid cancer?
In follow-up after thyroid cancer, thyroglobulin itself is measured in the blood as an indicator of remaining thyroid tissue. Anti-TG antibodies can interfere with that measurement, which can make the outcome unreliable. That is why the antibodies are routinely measured alongside it in that setting. Such monitoring runs through the treating specialist and is separate from the test you order here.
Do medicines or supplements affect the result?
Biotin from supplements can interfere with some thyroid tests. There are also medicines, such as amiodarone and lithium, that can affect the thyroid itself. Please tell us about your medication and supplements so our doctor can take this into account during interpretation.
How much does an anti-TG test cost?
A single anti-TG test costs €55. On top of that you pay a one-off €29 blood draw fee per order; it is waived from €225. Testing anti-TG on its own therefore comes to €84 all-in. If you want to measure how your thyroid is working at the same time, the Thyroid function package contains TSH and Free T4 for €69.
Ready for insight into your anti-TG level?
You receive your anti-TG level including a personal explanation from a doctor, typically within 2 working days. No referral required.
Order Anti-TG →Want to test multiple markers at once?
Combine Anti-TG with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
55,-
+ €29 blood draw fee+ €29 blood draw fee per order