Anti-TPO Antibodies: what your level actually means
Also known as: Thyroid Peroxidase Antibodies, TPO Antibodies, Anti-Thyroid Peroxidase · Updated 19 Aug 2026 · Educational — not medical advice
The short answer: Anti-TPO antibody levels are normally below about 34 IU/mL, and this test looks for antibodies that mistakenly target an enzyme involved in making thyroid hormone. A positive result, generally above roughly 34 IU/mL, points toward an autoimmune tendency such as Hashimoto's thyroiditis, but it is a marker of predisposition, not proof that thyroid disease is currently present or will definitely develop.
Where does your value sit?
This Anti-TPO Antibodies value is inside the normal range. Your lab's printed reference range takes precedence — ranges vary slightly between laboratories.
What Anti-TPO tells you
Anti-TPO antibodies target thyroid peroxidase, an enzyme the thyroid gland needs to produce hormone. Their presence indicates the immune system has begun reacting against thyroid tissue, which is the hallmark of autoimmune thyroid conditions like Hashimoto's thyroiditis and Graves' disease, though many people with positive antibodies have entirely normal thyroid function for years. (Illustration is schematic.)
Common reasons it rises
- Hashimoto's thyroiditis — the most common cause of a positive anti-TPO result, often preceding an underactive thyroid by years.
- Graves' disease — an overactive thyroid condition that can also show positive anti-TPO antibodies.
- Family history of autoimmune thyroid disease — a strong genetic component means relatives often share this tendency.
- Other autoimmune conditions — having one autoimmune disease modestly raises the chance of another, including thyroid antibodies.
And reasons it runs low
- No autoimmune thyroid activity — a negative result argues against Hashimoto's or Graves' disease as the cause of any thyroid symptoms.
- Adequately treated autoimmune thyroid disease — antibody levels can decline somewhat with long-term treatment in some people, though they rarely disappear entirely.
Does food or exercise change this?
Check with your doctor first: Anyone with a positive anti-TPO result should have thyroid function checked periodically, even if currently normal, especially during pregnancy planning.
General guidance for adults — not a personal diet plan. Your doctor or dietitian knows your full picture.
Checked against: MedlinePlus: Thyroid Antibodies · American Thyroid Association: Hashimoto's Thyroiditis (ATA) · American Thyroid Association: Thyroid Function Tests (ATA)
What to do next
Ask your doctor: “Given a positive result, should my thyroid function be monitored more closely even if it's currently normal?”
Ask your doctor: “Does this change how my thyroid symptoms should be evaluated?”
Ask your doctor: “Should my family be aware of an autoimmune thyroid tendency?”
Read together with
Questions people ask
Does a positive anti-TPO result mean I have thyroid disease?
Not necessarily. Many people carry positive antibodies for years with completely normal thyroid hormone levels. A positive result means the immune system is targeting the thyroid, which raises the chance of developing an underactive or overactive thyroid over time, so doctors often recommend periodic thyroid function checks rather than immediate treatment.
Can anti-TPO antibodies go away on their own?
They can fluctuate, and levels sometimes decrease over time, but they rarely disappear completely once present. Because of this, most doctors focus on monitoring thyroid hormone levels over time rather than tracking the antibody number itself once autoimmune thyroid disease has been identified.
Share this guide
One value tells half the story.
Upload your full report — every value checked and explained. Free — no account needed.