Insight into your anti-TPO level.
Anti-TPO are antibodies against the thyroid enzyme thyroid peroxidase. Their presence fits with an autoimmune thyroid condition such as Hashimoto's, and gives context to an abnormal thyroid result.
Also known as: TPO antibodies, anti-TPO, thyroid antibodies
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By the Bloodworks editorial team
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Background
What are anti-TPO antibodies?
Thyroid peroxidase, or TPO for short, is an enzyme in the thyroid needed to produce thyroid hormone. In some people, the immune system makes antibodies against this own enzyme: anti-TPO, also called TPO antibodies. Their presence shows that the immune system is directed at thyroid tissue. That fits with an autoimmune thyroid condition. The best known is Hashimoto's disease, in which a smouldering inflammation gradually damages the thyroid tissue, so the thyroid may slowly become underactive. TPO antibodies are also often detectable in Graves' disease, in which the thyroid is overactive because antibodies against the TSH receptor drive it on. Anti-TPO therefore does not distinguish between the two conditions; the value only shows that the immune system is involved.
Anti-TPO says something about the possible cause of a thyroid problem, not about 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. The three values complement each other. If TSH and Free T4 are normal while anti-TPO is detectable, the thyroid is currently working normally. The chance of the thyroid becoming underactive over time is somewhat higher, though, and people sometimes choose periodic monitoring of thyroid function. Antibodies are also found in people whose thyroid keeps working well throughout life, more often in women and at older ages. A detectable anti-TPO is therefore not a diagnosis in itself, and how high the value is says nothing about the severity of any condition or about your symptoms. The result gains meaning in combination with your thyroid function and your personal story.
In brief
Antibody
Directed against the thyroid enzyme TPO
Autoimmune
Fits with Hashimoto's and also occurs in Graves'
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
This marker is also included in
Testing several values in a single draw takes one blood collection and gives a more complete picture. The choice is yours.
Common reasons to test
When can insight into your Anti-TPO be valuable?
Below are some situations in which measuring Anti-TPO can provide insight.
Context for an abnormal thyroid value
If your TSH or Free T4 is abnormal, anti-TPO helps to understand whether the immune system plays a role, as in Hashimoto's or Graves' disease.
When Hashimoto's is suspected
With persistent symptoms that fit an underactive thyroid, such as fatigue, weight gain or feeling cold easily, anti-TPO is often added to the investigation.
With thyroid conditions in the family
Autoimmune thyroid conditions run in families. With a family history, anti-TPO gives 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, anti-TPO helps to place the result and to judge whether follow-up is worthwhile.
What your result means
Anti-TPO elevated or undetectable: what does your result mean?
Anti-TPO 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: anti-TPO does not measure how your thyroid is working, but the presence of antibodies. A result can therefore only be interpreted together with TSH and Free T4 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 Hashimoto's have no detectable anti-TPO. 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-TPO 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-TPO means antibodies against the thyroid enzyme are detectable. With an underactive thyroid, that fits with Hashimoto's disease; with an overactive thyroid, it can fit with Graves' disease. At the same time, an elevated value also occurs in people with a normally functioning thyroid and no symptoms. It is therefore not a diagnosis in itself, and how high the value is says nothing about severity. Our doctor assesses the result together with your thyroid function and explains whether follow-up or periodic monitoring is customary.
How we interpret your result
Our doctors interpret your anti-TPO 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-TPO.
A single marker gives one perspective. For a broader picture you can combine Anti-TPO 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 TPO antibodies?
TPO antibodies, also called anti-TPO, are antibodies the immune system makes against thyroid peroxidase. That is an enzyme in the thyroid needed to produce thyroid hormone. Detectable TPO antibodies show that the immune system is directed at thyroid tissue. That fits with an autoimmune thyroid condition, such as Hashimoto's disease.
Does an elevated anti-TPO mean I have Hashimoto's?
No. Detectable antibodies fit with an autoimmune thyroid condition, but are not a diagnosis in themselves. Antibodies also occur in people with a normally functioning thyroid and no symptoms. Your thyroid function, measured with TSH and Free T4, together with your symptoms, determines the picture. Our doctor explains what your result means in your situation.
What is the difference between Hashimoto's and Graves' disease?
Both are autoimmune thyroid conditions, but with opposite effects. In Hashimoto's, a smouldering inflammation damages the thyroid tissue, so the thyroid may become underactive. In Graves' disease, antibodies against the TSH receptor drive the thyroid on, making it overactive. Anti-TPO can be detectable in both and does not make that distinction. For that, a doctor looks at TSH and Free T4 and, if needed, further testing.
How much does an anti-TPO test cost?
A single anti-TPO 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-TPO on its own therefore comes to €84 all-in. If you want to measure the antibodies together with your thyroid function, the Thyroid function Extended package contains TSH, Free T4, Free T3 and anti-TPO for €169.
Do I need to fast for an anti-TPO test?
No, you do not need to fast for anti-TPO. You can have blood drawn at any time of day.
Is testing anti-TPO useful if my TSH is normal?
Thyroid function is usually the first step: TSH, often together with Free T4. Yet anti-TPO can be useful even with a normal TSH, for example with a wish to conceive, with thyroid conditions in the family or with another autoimmune condition. Detectable antibodies with a normal thyroid function do not mean treatment is needed. Periodic monitoring of TSH and Free T4 can be considered, though, because the chance of an underactive thyroid over time is somewhat higher.
Does the level of the antibodies say anything about severity?
No. A strongly elevated anti-TPO does not mean you have more symptoms or that a condition will follow a more serious course. The level of the antibodies does not track severity. This is also why anti-TPO is usually not repeated to follow a course over time.
What is the difference between anti-TPO and TSH?
TSH shows how your thyroid is working at this moment, under signalling from the pituitary gland. Anti-TPO shows whether your immune system is making antibodies against thyroid tissue. The first measures function, the second a possible cause. They complement each other.
Can I have anti-TPO without symptoms?
Yes. A share of people with detectable antibodies have a normally functioning thyroid and no symptoms at all. People with antibodies do sometimes choose periodic monitoring of thyroid function, because the chance of developing an underactive thyroid over time is somewhat higher. Our doctor will explain this.
How often should I have anti-TPO measured?
A single measurement is usually enough. Once the antibodies have been detected, repeating the same antibody test adds little. What people do instead is have their thyroid function checked periodically with TSH and Free T4.
Does my medication affect the result?
Biotin supplements can interfere with the measurement. Some medicines, such as amiodarone and lithium, can affect the thyroid. Please tell us about your medication and supplements so our doctor can take this into account during interpretation.
What do I do with my result?
You receive a PDF report with your value and a personal explanation from a doctor. The report is written in medical language, so you can discuss it with your GP if you wish. What you do with it remains entirely your choice.
How do I arrange an anti-TPO blood test without a referral?
You order the test online and choose one of the 1000+ collection points in the Netherlands yourself. A referral from a GP is not required. After the blood draw you receive your result with a personal explanation from a doctor, usually within 2 working days.
What does anti-TPO mean when trying to conceive or during pregnancy?
Thyroid antibodies are often included in questions around fertility and pregnancy, because thyroid function receives extra attention in that period. Detectable antibodies do not automatically mean there is a problem. Thyroid function is, however, checked more often with TSH and Free T4 in that situation. Please discuss a detectable anti-TPO with your GP or midwife if you are trying to conceive or are pregnant.
What is the difference between anti-TPO and anti-TG?
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 stores hormone. When the question is whether the immune system is involved, anti-TPO is used most often, because that antibody is the most frequently detectable. On this page you order anti-TPO.
In the Health Guide
Read more about this value
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Ready for insight into your anti-TPO level?
You receive your anti-TPO level including personal explanation from a doctor, typically within 2 working days. No referral required.
Order Anti-TPO →Want to test multiple markers at once?
Combine Anti-TPO with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
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