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Anti-TPO

Autoimmune disorder Biomarker

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Collection Type: Blood

Body System

Related System: Autoimmune disorder

Overview

Anti‑TPO (anti–thyroid peroxidase) antibodies are immune proteins directed against thyroid peroxidase, an enzyme required for thyroid hormone synthesis. The serum anti‑TPO test measures the presence and titre of these antibodies to detect autoimmune attack on the thyroid. Elevated anti‑TPO suggests autoimmune thyroid disease such as Hashimoto’s thyroiditis (most commonly) or Graves’ disease and can precede changes in thyroid function. Symptoms prompting testing include fatigue, unexplained weight change, cold or heat intolerance, goitre, palpitations, menstrual irregularities, hair loss, or infertility/miscarriage history. Levels are more commonly elevated in women, increase with age, may change in pregnancy/postpartum, and are more frequent in people with other autoimmune disorders or a family history of thyroid autoimmunity.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Autoimmune disorder (thyroid autoimmunity assessment) - Symptoms: fatigue, weight change, goitre, palpitations, menstrual irregularities, hair loss, infertility or recurrent miscarriage - Diagnoses/monitoring: supports diagnosis and monitoring of Hashimoto’s thyroiditis, Graves’ disease, postpartum thyroiditis - Reasons for abnormal levels: autoimmune thyroid disease, certain medications, postpartum changes, other autoimmune conditions - Biological meaning: indicates immune-mediated thyroid damage (higher titres = greater likelihood of ongoing autoimmunity) - Lifestyle/family: excess iodine exposure, some drugs (e.g., interferon, amiodarone), and a family history of autoimmune thyroid disease increase testing need

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Understanding Test Results

Values <35 IU/mL: generally considered negative/normal; low likelihood of clinically significant thyroid autoimmunity.
35–100 IU/mL: low to moderate elevation may reflect early or mild autoimmune activity; monitor thyroid function (TSH, free T4) periodically.
100–1000 IU/mL: clearly positive strongly suggests autoimmune thyroid disease (commonly Hashimoto’s; can occur with Graves’); higher risk of progression to hypothyroidism and may warrant endocrine follow‑up and thyroid function testing.
>1000 IU/mL: very high titre indicates active autoimmunity and substantial risk of thyroid dysfunction; assess and monitor thyroid hormone levels and symptoms closely.
Transient rises can occur postpartum or after certain medications; results must be interpreted with clinical context and repeat testing when indicated.

Normal Range

0–35 IU/mL

FAQs

Q: What does it mean if anti-TPO is high?

A: High anti‑TPO means your immune system is producing antibodies that attack the thyroid. It commonly indicates autoimmune thyroid disease (most often Hashimoto’s, sometimes Graves’), and raises the risk of thyroid inflammation and hypothyroidism. It can affect fertility and pregnancy. Further evaluation with TSH and free T4 tests, possible ultrasound, and endocrinology follow‑up is recommended.

Q: What is the normal range for anti TPO?

A: Normal (negative) anti‑TPO antibody levels are generally below about 35–60 IU/mL, with many laboratories using a cutoff near 35–40 IU/mL. Levels above the lab-specific reference range support a diagnosis of autoimmune thyroid disease (for example Hashimoto’s or Graves’). Always interpret anti‑TPO results against the reporting laboratory’s reference interval and review abnormal findings with your clinician.

Q: What to do if TPO is high?

A: If your TPO antibody level is high, see your doctor for repeat thyroid function tests (TSH, free T4) and clinical assessment. High TPO suggests autoimmune thyroid disease; your clinician may monitor levels, start levothyroxine if you’re hypothyroid, and refer a specialist—especially in pregnancy. Regular follow-up, symptom management, and screening for other autoimmune conditions are important. Discuss lifestyle and medication issues with your provider.

Q: Should TPO be high or low?

A: TPO (thyroid peroxidase antibodies) should be low or undetectable. Elevated anti‑TPO levels indicate autoimmune thyroid disease (e.g., Hashimoto’s or Graves’) and increased risk of thyroid dysfunction. High TPO antibodies require correlation with TSH and free T4, clinical assessment, and follow‑up with a healthcare provider for monitoring and possible treatment.

Q: Can anti-TPO be cured?

A: Anti‑TPO antibodies indicate autoimmune thyroid disease (e.g., Hashimoto’s). They usually cannot be fully \

Q: What if TPO is high but TSH is normal?

A: Elevated anti‑TPO antibodies with normal TSH suggests autoimmune thyroiditis (often early Hashimoto’s) while thyroid function remains normal. It raises risk of future hypothyroidism and can affect pregnancy. Management is periodic TSH monitoring, watching for symptoms, and discussing ultrasound or endocrine referral. Treatment isn’t always needed unless TSH or symptoms worsen, or in pregnancy when levothyroxine thresholds may be lower.