Quick answer: TPO (thyroid peroxidase) antibodies are produced when the immune system targets an enzyme the thyroid uses to make hormone. Elevated TPO antibodies are the most common marker of Hashimoto’s thyroiditis, the leading cause of hypothyroidism, and can be present before thyroid function clearly changes. They are also seen in Graves’ disease and sometimes in people with normal thyroid function.
What is TPO Antibodies?
Thyroid peroxidase is an enzyme the thyroid uses to attach iodine and make hormones. TPO antibodies are autoantibodies against this enzyme. This marker is part of the Healthspan Assessment panel available to my 1-on-1 patients.
Why TPO Antibodies matters
- Identifies autoimmune thyroid disease
- Helps predict future hypothyroidism
- Important before and during pregnancy
Understanding your result
Reference ranges vary by lab, age and sex. Your provider interprets your result against the lab’s range and your overall picture, rather than chasing a single number. Functional labs are optional. They can be helpful in more complex cases, and in my practice they are available only to patients working 1-on-1 with me.
What elevated TPO antibodies can mean
- Hashimoto’s thyroiditis
- Graves’ disease
- Other autoimmune conditions
- After pregnancy (postpartum thyroiditis)
What affects TPO Antibodies
- Genetics and family history
- Pregnancy
- Excess iodine in some people
- Other autoimmune conditions
Ways to support healthy levels
- Monitor TSH and free T4 over time with your provider
- Eat a nutrient-dense diet with selenium-rich foods
- Avoid high-dose iodine supplements
- Support gut health (see gut health and autoimmunity)
- Check thyroid closely if pregnant or planning pregnancy
TPO Antibodies and healthy aging
Autoimmunity becomes more common with age as immune regulation shifts and inflammation rises. Spotting thyroid autoimmunity early allows timely monitoring.
Related thyroid tests: TSH, free T4, free T3, reverse T3, thyroglobulin antibodies.
When to see a naturopathic doctor
- Fatigue, weight change, feeling cold or hot, hair loss or constipation
- Anxiety, palpitations or tremor
- Irregular periods or trouble conceiving
- A family history of thyroid disease
- Abnormal thyroid results you want explained
See a medical provider promptly for a racing or irregular heartbeat, severe confusion or drowsiness, a rapidly growing neck lump, or trouble swallowing or breathing.
Want help making sense of your labs?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Frequently asked questions
Do positive TPO antibodies mean I have Hashimoto’s?
Often, especially with symptoms or abnormal TSH, but some people with positive antibodies have normal thyroid function.
Can TPO antibodies go down?
They can fluctuate; the main goal is protecting thyroid function.
Should I test TPO if my TSH is normal?
It can be useful with symptoms, family history or pregnancy plans.
Does gluten affect Hashimoto’s?
People with Hashimoto’s should be screened for celiac disease; others can discuss a trial with their provider.
Sources
- Ralli M, et al. Hashimoto’s thyroiditis: an update on pathogenic mechanisms, diagnostic protocols, therapeutic strategies, and potential malignant transformation. Autoimmun Rev 2020. PMID: 32805423. https://pubmed.ncbi.nlm.nih.gov/32805423/
- Huber G, et al. Prospective study of the spontaneous course of subclinical hypothyroidism: prognostic value of thyrotropin, thyroid reserve, and thyroid antibodies. J Clin Endocrinol Metab 2002. PMID: 12107228. https://pubmed.ncbi.nlm.nih.gov/12107228/
- Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol 2014. PMID: 24342882. https://pmc.ncbi.nlm.nih.gov/articles/PMC3976240/
- Ventura M, Melo M, Carrilho F. Selenium and thyroid disease: from pathophysiology to treatment. Int J Endocrinol 2017. PMID: 28255299. https://pmc.ncbi.nlm.nih.gov/articles/PMC5307254/
- MedlinePlus: Thyroid Antibodies
- NIDDK: Hashimoto’s Disease
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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