What this marker measures
TPO antibodies are typically ordered when TSH is abnormal or when autoimmune thyroid disease is suspected (e.g. family history, goitre, recurrent miscarriage). The presence of antibodies does not by itself require treatment.
High or low: what it can mean
High TPO Antibodies
Elevated TPO antibodies are strongly associated with Hashimoto's thyroiditis and Graves' disease. They may be present years before thyroid function abnormalities appear and are also more common in pregnancy-related thyroid changes.
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Low TPO Antibodies
A negative (low) result is normal and suggests autoimmune thyroid disease is unlikely. A small percentage of healthy individuals can have low-level antibodies without thyroid dysfunction.
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Frequently asked questions
What is TPO Antibodies?
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TPO antibodies are autoantibodies directed against thyroid peroxidase, an enzyme involved in thyroid hormone production. Their presence is a marker of autoimmune thyroid disease.
What does TPO Antibodies measure?
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TPO antibodies are typically ordered when TSH is abnormal or when autoimmune thyroid disease is suspected (e.g. family history, goitre, recurrent miscarriage). The presence of antibodies does not by itself require treatment.
What does high TPO Antibodies mean?
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Elevated TPO antibodies are strongly associated with Hashimoto's thyroiditis and Graves' disease. They may be present years before thyroid function abnormalities appear and are also more common in pregnancy-related thyroid changes.
What does low TPO Antibodies mean?
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A negative (low) result is normal and suggests autoimmune thyroid disease is unlikely. A small percentage of healthy individuals can have low-level antibodies without thyroid dysfunction.
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.