Anti Tpo
Antibodies against thyroid peroxidase, an enzyme in the thyroid. Raised levels indicate autoimmune thyroid disease (e.g. Hashimoto's).
Typical reference range
| Range | Unit |
|---|---|
| 0–35 | kU/l |
What Anti Tpo measures
Anti-TPO (thyroid peroxidase antibodies) are immune antibodies directed against thyroid peroxidase, an enzyme the thyroid gland uses to make thyroid hormones. Their presence is a marker of autoimmune thyroid disease, meaning the immune system is reacting against thyroid tissue.
- They are usually checked alongside TSH and thyroid hormones when an autoimmune thyroid condition is suspected.
- They help clarify the cause behind an abnormal thyroid picture rather than measure thyroid activity itself.
Anti-TPO is one piece of a broader thyroid assessment. It reflects immune activity, not how much hormone the thyroid is producing, so it is interpreted together with the other thyroid results by a clinician.
What a high Anti Tpo can mean
A high (positive) anti-TPO indicates thyroid autoimmunity, meaning the immune system is producing antibodies against the thyroid.
- Positive antibodies are commonly found in Hashimoto's thyroiditis, and can also appear in Graves' disease.
- Positive antibodies alongside an abnormal TSH support an autoimmune cause for the thyroid picture.
- They can raise the chance that a borderline thyroid picture progresses over time.
Importantly, many people have positive anti-TPO antibodies while their thyroid function stays normal, so a positive result on its own does not mean thyroid disease is present. Interpretation belongs with a clinician, who weighs the antibody result together with TSH, thyroid hormones, symptoms, and your overall history.
What a low Anti Tpo can mean
A low or negative anti-TPO means these antibodies were not detected in the blood.
- This makes autoimmune thyroid disease less likely as a cause of a thyroid problem.
- It does not completely rule out thyroid problems, which are assessed mainly through TSH and thyroid hormones.
In other words, a negative antibody result lowers the probability of an autoimmune cause but says little about whether the thyroid is currently overactive or underactive. Thyroid activity itself is judged by the other thyroid tests, not by this antibody. A clinician interprets the whole thyroid picture together, combining antibody status with hormone levels, symptoms, and your history before drawing any conclusions.
Track your Anti Tpo over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.