Anti-TPO antibodies
Anti-TPO antibodies are autoantibodies against a thyroid enzyme. Their presence means the immune system is attacking its own thyroid — a hallmark of autoimmune thyroid diseases.
| Rating | Range | What it means |
|---|---|---|
| Good | below 34 IU/mL | Negative — no sign of autoimmune thyroid disease. |
| Talk to a doctor | 34 IU/mL and above | Elevated — possible autoimmune thyroid disease (Hashimoto); seek advice. |
Why it matters
ETA: an elevated level indicates autoimmune thyroid disease (e.g. Hashimoto).
If it’s low
Low/absent anti-TPO mean an autoimmune cause is unlikely — reassuring.
If it’s high
Elevated anti-TPO indicate autoimmune activity in the thyroid. They do not necessarily mean disease now, but they increase the likelihood of future hypothyroidism; TSH must be monitored.
What to do
Positivity alone is not a disease — it is important to monitor TSH/fT4. In pregnancy and when planning one, it is worth knowing (a higher risk of disorders).
Read together with
TSH · fT4 (free thyroxine)
Part of the guide: Thyroid →
Articles about this marker
- Hashimoto's: what it is, what is proven to help and what the latest research saysMarker explained
- Thyroid: which tests tell you what, and how to do them properlyMarker explained
- TSH: normal values, what a high TSH means and when it is a diseaseThyroid
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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