Thyroid Peroxidase (TPO) & Thyroglobulin Antibodies Test

Thyroid peroxidase and thyroglobulin are proteins involved in how the thyroid makes its hormones. In some people, the immune system produces antibodies against these proteins. This test measures both the TPO antibodies and the thyroglobulin antibodies in the same blood sample, so a clinician can see the two markers together. The presence of these antibodies is associated with autoimmune thyroid conditions, though they are always interpreted 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 antibody markers describe immune activity rather than thyroid hormone levels, they are often considered alongside markers like TSH and T4, and a clinician reads the whole picture rather than any single result.

People who order this test are often exploring whether an immune process may be involved in their thyroid picture, sometimes after other thyroid markers have prompted a closer look, or because autoimmune thyroid conditions run in their family. Measuring both antibodies together appeals to people and clinicians who want a broader view of thyroid autoimmunity in a single draw rather than checking one antibody at a time.

Thyroid peroxidase and thyroglobulin are both proteins the thyroid relies on to build its hormones. In some people the immune system produces antibodies aimed at these proteins, and that immune activity is what this test looks at. Rather than measuring hormone levels, it describes whether the body is generating antibodies against its own thyroid machinery.

The presence of these antibodies is associated with autoimmune thyroid conditions, such as Hashimoto's thyroiditis. That association is meaningful, but antibodies are only one thread in a larger picture and are never read as the whole story.

TPO and thyroglobulin antibodies point at different proteins, and each contributes its own piece of information about thyroid autoimmunity. Bundling them into a single draw lets a clinician see the two markers side by side rather than checking one and later circling back for the other. For people exploring whether an immune process is involved, that combined view can be a more efficient starting point.

Because these markers reflect immune activity rather than thyroid output, they are often considered alongside hormone markers like TSH and free T4.

Collection is a quick, walk-in blood draw at a patient service center, with a phlebotomist taking a small sample from a vein in the arm. Results are posted to the account once the laboratory finishes. A clinician interprets antibody results in context — weighing symptoms, personal and family history, and hormone markers — rather than drawing conclusions from the antibodies alone.

Results will be emailed securely to you as a PDF.