Home › Biomarkers › TPO antibodies
According to MedlinePlus, you have a higher risk of an autoimmune thyroid condition if you are over 50. If other thyroid tests come back too high or too low, your healthcare provider may use this test.[1]
On this page you can read what TPO antibodies are, what the guidelines say about a level that is too low or too high, what affects your level and which levels are best to look at alongside it.
Also known as: anti-TPO, TPOAb, thyroid peroxidase antibodies, thyroid antibodies, antimicrosomal antibodies. At the lab: MAK.
Your thyroid is a small, butterfly-shaped gland in your neck. It makes hormones that control many processes in your body. Think of your heart rate and how quickly you burn calories from food.[1]
Antibodies are proteins your immune system makes against germs, such as viruses and bacteria. Sometimes antibodies attack your own healthy tissue, because your body mistakes it for something foreign. These antibodies are called autoantibodies. Your body makes them by mistake.[1]
TPO antibodies are one of these autoantibodies. They target a protein that helps your thyroid make hormones. This means they can affect your thyroid's ability to make healthy amounts of hormone.[1]
If your thyroid is underactive, it makes too little hormone. Many functions in your body then slow down. Think of gaining weight, tiredness, hair loss, finding it hard to cope with cold, irregular periods, constipation, a low mood and pain in your joints.[1]
If your thyroid works too fast, your body's functions actually speed up. Think of dropping weight, shaky hands, poor sleep, feeling anxious, a faster heartbeat, not coping well with heat, bulging eyes and a swollen thyroid.[1]
With symptoms like these, a thyroid antibody test can show whether your immune system is behind the problem. Your healthcare provider also looks at other tests, your symptoms and your own and your family's medical history.[1]
If you are pregnant, a thyroid condition can harm you and your unborn baby. That is why MedlinePlus considers it important to get tested as soon as you know you are pregnant.[1]
The Labplusarts lab uses a reference range of 0 to 34 kU/l for TPO antibodies. The lab calls a level within these limits normal.[2]
| Result | What it can mean | Who it is for |
|---|---|---|
| Negative: no thyroid antibodies found[1] | Your thyroid symptoms are probably not caused by an autoimmune condition | People with thyroid symptoms |
| Positive: TPO antibodies found, sometimes together with thyroglobulin antibodies[1] | Can point to an autoimmune condition in which the thyroid works too slowly | People whose other thyroid tests came out too high or too low |
| Positive: TPO antibodies found, sometimes together with TSI or TRAb[1] | Can point to an autoimmune condition in which the thyroid works too fast or too slowly | People whose other thyroid tests came out too high or too low |
| The more antibodies[1] | The greater the chance of an autoimmune thyroid condition | Everyone who has had the test |
Source: MedlinePlus, U.S. National Library of Medicine. Thyroid antibody test results, for people whose thyroid is being examined by a doctor.[1]
A negative result means no thyroid antibodies were found. According to MedlinePlus, your thyroid symptoms are then probably not caused by an autoimmune condition.[1]
According to MedlinePlus, a high level can point to an autoimmune condition as the cause of an underactive thyroid. A positive result can also point to an autoimmune condition that makes the thyroid overactive. The more antibodies you have, the greater the chance of such a thyroid condition.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
MedlinePlus lists a higher risk of an autoimmune thyroid condition if you are a woman, if such thyroid conditions run in your family or if you already have another autoimmune condition.[1]
According to MedlinePlus, thyroid surgery or radiation to your neck is also linked to a higher risk.[1]
If you take medicines that contain a lot of iodine, your risk of an autoimmune thyroid condition may be higher, according to MedlinePlus.[1]
No special preparation is needed for a blood test for thyroid antibodies.[1]
TPO antibodies are included in BioProfile 150.[3]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
