Thyroid Peroxidase (TPO) Antibodies Test
A Thyroid Peroxidase (TPO) Antibodies test measures antibodies directed at thyroid peroxidase, an enzyme the thyroid uses to make its hormones. These antibodies are associated with autoimmune thyroid conditions.
About this test
Thyroid peroxidase, or TPO, is an enzyme that plays a role in producing thyroid hormones. In some people, the immune system makes antibodies against this enzyme. The TPO antibodies test measures the level of these antibodies in the blood on their own, focusing specifically on this single marker rather than pairing it with other antibodies. Their presence is associated with autoimmune thyroid conditions, and it is always understood in a broader clinical context.
The test is performed with a routine blood draw at a patient service center, where a phlebotomist collects a sample from a vein in the arm and sends it to the laboratory. People follow any preparation guidance from their ordering clinician. Because this marker reflects immune activity rather than thyroid hormone levels, it is often considered alongside markers like TSH and T4, with a clinician reading the whole picture rather than a single result.
Who commonly orders it
People who order a TPO antibodies test on its own are often looking into whether an immune process may be involved in their thyroid picture, sometimes after other thyroid markers prompted a closer look, or because autoimmune thyroid conditions run in their family. Choosing TPO antibodies alone appeals to people and clinicians who want to focus on this single, widely used antibody marker.
The immune side of the thyroid
Thyroid peroxidase is an enzyme the thyroid uses to build its hormones. In some people, the immune system produces antibodies aimed at this enzyme, and that is what the TPO antibodies test looks at. It describes immune activity toward the thyroid rather than the level of thyroid hormones themselves.
The presence of TPO antibodies is associated with autoimmune thyroid conditions, such as Hashimoto's thyroiditis. That link is why the marker is so widely used, but antibodies are only part of the picture and are always understood alongside other information.
Choosing TPO antibodies on their own
This test focuses on a single, well-established antibody marker rather than combining it with thyroglobulin antibodies as a broader panel would. Some people and clinicians prefer that narrower focus when TPO is the specific marker they want to look at — often after other thyroid results have prompted a closer look, or because autoimmune thyroid conditions run in the family. Because it reflects immune activity, it is commonly considered next to hormone markers like TSH and free T4.
What to expect and how results are read
The sample is collected with a quick, walk-in blood draw at a patient service center, where a phlebotomist takes a small amount from a vein in the arm. Results are posted to the account once the laboratory reports them. A clinician interprets TPO antibodies in context — with symptoms, history, and other markers — rather than treating the antibody result as the whole answer.
Your results
Results will be emailed securely to you as a PDF.
Order Thyroid Peroxidase Antibodies in a panel
Thyroid Peroxidase Antibodies (TPO) isn't sold on its own online — it's included in these physician-ordered panels:
- ✓ Physician order included · results in 24–72 hrs
Prefer just this single marker? Request it →
Prefer a fuller panel?
A curated bundle groups this test with the markers clinicians most often review alongside it — often better value than single tests.
Frequently asked questions
What does the TPO antibodies test measure?+–
It measures antibodies directed at thyroid peroxidase, an enzyme involved in making thyroid hormones. The level of these antibodies is reported on its own in this test.
What are TPO antibodies associated with?+–
Their presence is associated with autoimmune thyroid conditions. Antibodies alone do not tell the whole story, so a clinician interprets them with symptoms, history, and other markers.
How is this different from an antibody panel?+–
This test focuses on TPO antibodies alone, while a broader panel may measure TPO antibodies together with thyroglobulin antibodies. The choice depends on what a clinician is evaluating.
How is the sample collected?+–
With a routine blood draw at a patient service center. A phlebotomist takes a small sample from a vein in the arm and sends it to the laboratory.
Is this an antibody test or a hormone test?+–
It is an antibody test. It reflects immune activity toward a thyroid enzyme rather than thyroid hormone levels, so it is often considered alongside hormone markers like TSH and T4.