Can this result diagnose a condition on its own?

No. Hormone tests are interpreted together with symptoms, medical history, and other laboratory results.

Which reference range should I use?

Use the reference interval provided by the laboratory that performed your test.

When should I discuss the result with a healthcare professional?

Results that are clearly outside range, persistent, or inconsistent with symptoms should be reviewed by a healthcare professional.

Information about a laboratory test

Anti-TPO (TPOAb): What Does This Blood Test Measure?

Detects antibodies made by the immune system against thyroid peroxidase.

Test summary

Test name: Anti-TPO (TPOAb)
Abbreviations: TPOAb, Anti-TPO
Category: Endocrinology / Thyroid Autoimmunity
Panel: Thyroid Antibody Tests
Specimen: Serum / plasma
Common units: IU/mL, kIU/L

What does the test measure?

Detects antibodies made by the immune system against thyroid peroxidase.

Why is the test ordered?

Helps evaluate autoimmune thyroid disease, especially Hashimoto thyroiditis.

Information about a low result

Low or negative Anti-TPO does not completely exclude autoimmune thyroid disease; context matters.

Information about a high result

High Anti-TPO may occur in autoimmune thyroid disease; the antibody level alone does not show the degree of thyroid dysfunction.

Reference and clinical context

Use the reference interval printed on your own laboratory report first. Hormone results may vary with the assay, age, sex, pregnancy, menstrual-cycle phase, and sampling time.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

Anti-TPO is different from TSH or free T4: it reflects antibody presence rather than directly measuring thyroid hormone production.

Related specialties

Endocrinology
Internal Medicine
Rheumatology
Obstetrics and Gynecology

Frequently asked questions

More information about this test

High Anti-TPO (TPOAb): What Does It Mean?

Sources

Hashimoto's Disease — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
U.S. government medical reference · 2026 · Hashimoto disease; TSH/T4/T3 and TPO antibody context · Verified: Aug 11, 2026
Thyroid Antibodies — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2023 · TPOAb, TgAb and TRAb; autoimmune-thyroid context · Verified: Aug 11, 2026