Summary

Thyroid peroxidase (TPO) is an enzyme that plays a key role in producing thyroid hormones. The measurement of anti-TPO antibodies is often used as an indicator of thyroid diseases, specifically autoimmune thyroid diseases.

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Overview

Antibodies are protective proteins that are part of the immune system. However, sometimes, they attack your body cells, producing autoimmune responses. The TPO enzyme is integral to the synthesis of thyroid hormones. Anti-TPO antibodies can disrupt this process, damaging the thyroid cells. When thyroid hormone production is affected, it can lead to various health problems, ranging from hypothyroidism to hyperthyroidism.^[1]

Increased levels of anti-TPO antibodies in the blood is typically a sign of autoimmune thyroid disorders, such as Hashimoto's and Graves' diseases.

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What should you know about this biomarker?

Like other biomarkers, anti-TPO is not only a diagnostic tool but also a prognostic indicator. Increased levels of anti-TPO may indicate a health issue, such as Hashimoto's thyroiditis or Graves' disease. However, anti-TPO antibodies can also be an early marker of future thyroid dysfunction, even before changes in traditional thyroid markers such as TSH and FT4 are observed. ^[1]

Each laboratory uses different machines and protocols, so the results might vary in terms of the reference ranges or used units of measurement. 

In Macromo blood tests, we use kUl/l (kilounits per liter), but you may also find values in IU/ml (international units per millimeter) on the internet.

Optimal anti-TPO (antibodies to TPO) levels vary depending on age, gender, and health status. However, typically, the reference range is under 34 kU/L.

There are two possible states of your blood test result: positive and negative.^[2] 

• A positive result will confirm the presence of TPO antibodies. Your doctor may order more tests to confirm the diagnosis of thyroid disease or to determine the cause and stage of your condition.
• A negative anti-TPO antibody test is considered normal. The thyroid peroxidase antibodies can't be too low.

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Genetics

Genetics may have the potential to affect circulating anti-TPO levels. Genetic changes affecting the TPO gene can lead to congenital hypothyroidism, characterized by very low levels of thyroid hormones from birth.^[3] 

In a large population study focused on middle-aged and elderly people, it was discovered that female sex and current smoking status are significantly connected to detectable and positive levels of TPO antibodies.^[4]  

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Recommendations

If your test results are outside the reference range, it is good to take some of the steps listed below:

• Consider making changes to your lifestyle. This may include maintaining a balanced diet, exercising regularly, avoiding smoking, and managing stress. 
• Make sure to stay properly hydrated, as hydration can indirectly support thyroid function. 
• Your doctor may order more tests to confirm the diagnosis of thyroid disease or to determine the cause and stage of your condition. 
• If you've been prescribed medication to manage your thyroid function or other related conditions, adhering to the prescribed regimen is crucial. 
• Monitor and report any new or worsening symptoms, such as fatigue, weight changes, hair loss, mood changes, heat or cold intolerance, change in bathroom habits, etc. 
• If planning a pregnancy, close monitoring is required.

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The information and tests provided on our website are for educational purposes only and are not a substitute for professional medical advice. Always consult with your healthcare provider before making health decisions. Our tests do not diagnose or treat diseases. Individual results may vary and should be discussed with a healthcare provider.