What It Measures
This test measures the level of antibodies in your blood that target thyroid peroxidase (TPO), an enzyme in the thyroid gland essential for producing thyroid hormones T3 and T4. The presence of these antibodies indicates your immune system is attacking your own thyroid tissue.
Thyroid peroxidase antibodies (TPO-Ab) are autoantibodies directed against thyroid peroxidase, a key enzyme involved in thyroid hormone synthesis. Elevated TPO antibodies are the most common marker of autoimmune thyroid disease and are found in the majority of patients with Hashimoto's thyroiditis and Graves' disease. Monitoring TPO-Ab levels helps assess autoimmune thyroid risk and guide treatment decisions.
Current Value
What High Means
Elevated TPO antibodies indicate active autoimmune attack on the thyroid gland. High levels are strongly associated with Hashimoto's thyroiditis (autoimmune hypothyroidism) and Graves' disease (autoimmune hyperthyroidism). Even in individuals with normal TSH, elevated TPO-Ab confers a significantly increased risk of developing overt thyroid dysfunction over time. Higher titers generally correlate with more aggressive autoimmune destruction and greater likelihood of progression to clinical hypothyroidism. Elevated TPO-Ab is also associated with increased risk of miscarriage, postpartum thyroiditis, thyroid nodules, and rarely thyroid lymphoma.
Possible Symptoms
Fatigue, weight gain or difficulty losing weight, cold intolerance, hair loss, dry skin, brain fog, depression, constipation, muscle weakness, joint pain, puffy face, elevated cholesterol, menstrual irregularities, difficulty concentrating, neck swelling or goiter. Note: some individuals with elevated TPO-Ab may be asymptomatic for years before thyroid dysfunction manifests.
What Low Means
Low or undetectable TPO antibodies are normal and indicate no significant autoimmune activity against the thyroid gland. This is the desired state. Approximately 5-10% of healthy individuals may have mildly elevated TPO-Ab without clinical disease, but truly low levels suggest the thyroid is not under autoimmune attack.
Possible Symptoms
Low/normal TPO antibodies do not cause symptoms — this is the healthy state. No symptoms are associated with low TPO-Ab levels.
Risk Factors
Hashimoto's thyroiditis, Graves' disease, hypothyroidism, hyperthyroidism, postpartum thyroiditis, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, celiac disease, primary adrenal insufficiency, miscarriage and infertility, family history of autoimmune thyroid disease, female sex (5-10x more common in women), iodine excess, selenium deficiency, vitamin D deficiency, chronic stress, environmental toxins, intestinal permeability (leaky gut)
Actionable Advice
Supplements
- •Selenium (200mcg selenomethionine)
- •Vitamin D3
- •Zinc
- •Omega-3 fatty acids (EPA/DHA)
- •Myo-inositol
- •N-acetyl cysteine (NAC)
- •Magnesium
- •Vitamin B12
- •Curcumin
- •Nigella sativa (black seed oil)
Diet & Lifestyle
- •Adopt a gluten-free diet — gluten molecular mimicry with thyroid tissue is well-documented in autoimmune thyroid disease
- •Reduce or eliminate dairy, especially if sensitivity is present
- •Manage stress through meditation, yoga, or breathwork — cortisol dysregulation worsens autoimmunity
- •Prioritize 7-9 hours of quality sleep
- •Avoid excessive iodine supplementation which can worsen TPO-Ab levels
- •Address gut health — consider elimination diet to identify food sensitivities
- •Reduce exposure to environmental toxins (BPA, pesticides, heavy metals)
- •Exercise moderately — avoid overtraining which can increase inflammation
- •Limit alcohol consumption
- •Consider low-dose naltrexone (LDN) with physician guidance for autoimmune modulation
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Ask questions about your TPO Antibodies results, trends, and what you can do to optimize.
Historical Trend
Related Biomarkers
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2026-01-28 | 3 IU/mL | 0.0 |
| 2025-08-25 | 3 IU/mL | — |