Thyroid
Anti-TPO
LOINC 5382-1 · IU/mL
What it is
Anti-TPO antibodies target thyroid peroxidase, an enzyme the thyroid uses to make hormones. They are the most common thyroid autoantibody.
Why it matters
Their presence helps confirm autoimmune thyroid disease, such as Hashimoto's or Graves' disease.
What high values can mean
A higher value indicates the immune system is reacting against the thyroid, common in autoimmune thyroid conditions.
What low values can mean
A low or negative value means little or no such antibody is found.
How to improve it
Antibody levels are not changed by lifestyle; care focuses on thyroid function and symptoms.
Food & lifestyle
No diet removes these antibodies; following your clinician's plan for thyroid health is the aim.
Preparing for the test
A blood test; fasting is not required — follow your lab's instructions.
When to talk to a doctor
Discuss positive anti-TPO with a doctor, interpreted with TSH and thyroid hormones.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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