Understanding Anti-TPO: Normal vs Optimal Ranges

?What is Anti-TPO?

Anti-thyroid peroxidase antibodies (Anti-TPO or TPOAb) target the enzyme thyroid peroxidase, which catalyses the synthesis of thyroid hormones. Anti-TPO is the most sensitive and specific marker for autoimmune thyroid disease, present in 95% of Hashimoto's thyroiditis and 75% of Graves' disease patients.

!Why It Matters

Elevated Anti-TPO is the strongest predictor of progression to overt hypothyroidism in patients with subclinical hypothyroidism (elevated TSH with normal T4). Anti-TPO elevation in euthyroid individuals with a family history of thyroid disease confers a significant lifetime risk of developing hypothyroidism. In pregnancy, elevated Anti-TPO substantially increases risk of postpartum thyroiditis and miscarriage.

Reference Ranges

Lab normal ranges may vary between laboratories. Optimal and longevity targets are based on research literature and should be interpreted with your physician.

Symptoms of Imbalance

• Hypothyroidism: fatigue, weight gain, dry skin, hair loss, cold intolerance, depression
• Anti-TPO elevation may precede symptoms by years

How to Improve Your Levels

• 1Selenium supplementation (200 mcg/day) reduces Anti-TPO titres — supported by multiple RCTs
• 2Optimise vitamin D levels
• 3Low-dose naltrexone (LDN) has emerging evidence in autoimmune thyroid disease
• 4Treat coeliac disease if co-present — gluten-free diet may reduce antibody titres

When to Test

Initial thyroid workup for autoimmune disease; every 1–3 years if positive but euthyroid; in early pregnancy in women with thyroid history.

Related Biomarkers