TPO antibodies blood test
Thyroid peroxidase antibodies
In short
A typical adult TPO antibodies result is under 9 IU/mL. Positive TPO antibodies are common: about 1 in 10 people with a well-working thyroid have them. They raise the chance that the thyroid slows down over the years. Always read your result against the range printed on your own report.
Immune proteins aimed at an enzyme inside the thyroid.
Thyroid peroxidase (TPO) is an enzyme the thyroid needs to make its hormones. These antibodies are the most common blood marker of Hashimoto's, an immune condition that can slow the thyroid. Doctors often check them when TSH is out of range, to look for a cause.
Is my TPO antibodies high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Adults | under 9 | IU/mL |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your TPO antibodies is high
Positive TPO antibodies are common: about 1 in 10 people with a well-working thyroid have them. They raise the chance that the thyroid slows down over the years.
Common reasons
- Found in many healthy people, especially women and older adults
- Hashimoto's, the most common cause of an underactive thyroid
- Graves' disease, an immune condition that makes the thyroid overactive
- Thyroid inflammation in the year after giving birth
- Other immune conditions, such as type 1 diabetes or a B12 absorption problem
What can throw it off
Labs use different methods and cut-offs, so results from two labs can't be compared directly, and biotin, a hair-and-nail supplement, can distort some tests.
Questions to take to your appointment
- 1How often should my TSH be checked from now on?
- 2Does the antibody level matter, or just that they are there?
- 3Do my TSH and free T4 show any effect on my thyroid yet?
Read together with
Doctors rarely read TPO antibodies alone. These usually sit next to it.
Quick answers
What is the TPO antibodies blood test?
TPO antibodies (Thyroid peroxidase antibodies): Immune proteins aimed at an enzyme inside the thyroid. Thyroid peroxidase (TPO) is an enzyme the thyroid needs to make its hormones. These antibodies are the most common blood marker of Hashimoto's, an immune condition that can slow the thyroid. Doctors often check them when TSH is out of range, to look for a cause.
What is a normal TPO antibodies level?
For most adults, TPO antibodies is typically under 9 IU/mL. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high TPO antibodies mean?
Positive TPO antibodies are common: about 1 in 10 people with a well-working thyroid have them. They raise the chance that the thyroid slows down over the years. Common reasons include found in many healthy people, especially women and older adults; Hashimoto's, the most common cause of an underactive thyroid; Graves' disease, an immune condition that makes the thyroid overactive; and thyroid inflammation in the year after giving birth. A doctor reads it together with your other results and how you feel.
What can affect my TPO antibodies result?
Labs use different methods and cut-offs, so results from two labs can't be compared directly, and biotin, a hair-and-nail supplement, can distort some tests.
What should I ask my doctor about my TPO antibodies?
Questions worth taking to the appointment: How often should my TSH be checked from now on? Does the antibody level matter, or just that they are there? Do my TSH and free T4 show any effect on my thyroid yet?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
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