Thyroid Peroxidase Antibodies

July 21, 2020

What is Thyroid Peroxidase (TPO)?

Thyroid Peroxidase (TPO) antibodies are a biomarker used to detect the presence of autoimmune thyroid disease. These antibodies develop when the immune system mistakes the components of the thyroid gland or its proteins as foreign. Therefore, if thyroid disease is present, TPO antibody levels will be high.

What role does Thyroid Peroxidase antibodies play in the body?

The thyroid is a small, butterfly-shaped gland in the neck. It produces the hormones triiodothyronine (T3) and thyroxine (T4) which are vital for cellular metabolism in the human body. If the thyroid produces too much of these hormones it causes hyperthyroidism, where the cells work faster than usual. If, however, the thyroid produces too little of these hormones then it can cause hypothyroidism.

Thyroid peroxidase (TPO) is an enzyme which is normally present in the thyroid gland and has an important role in the production of thyroid hormones. A presence of TPO antibodies in the blood usually suggest an autoimmune thyroid disorder, such as Hashimoto’s or Grave’s disease.

How does Thyroid Peroxidase affect my wellbeing?

If levels of TPO antibodies are significantly increased then it frequently indicates that there is an autoimmune thyroid disease such as Hashimoto’s disease or Graves’ disease. Usually, the higher the level of TPO antibodies, the more likely an autoimmune disease is.

Hashimoto’s disease causes an underactive thyroid or hypothyroidism. Because your immune system attacks the thyroid, the gland is damaged and it is unable to produce enough thyroid hormones.

The symptoms of Hashimoto’s are like those of hypothyroidism and include:

  • Weight gain
  • Tiredness
  • Joint and muscle pain
  • Constipation
  • Dry, thin hair
  • Depression
  • Slow heart rate
  • Memory issues

Graves’ disease, on the other hand, is a thyroid autoimmune disease that causes hyperthyroidism. Your immune system attacks the thyroid gland and causes it to make more thyroid hormones that your body needs.

If you have Grave’s disease, you may have some of the common symptoms of an overactive thyroid, like:

  • Fast and irregular heartbeat
  • Goitre (a large swelling in your neck)
  • Diarrhoea or frequent bowel movements
  • Tiredness
  • Muscle weakness
  • Trembling hands
  • Trouble sleeping
  • Weight-loss

How can I improve my result?

Scientists are not sure why the body’s immune system attacks the thyroid gland, causing autoimmune disease, but it is likely to be a combination of genetics and environmental factors.

People who have an autoimmune disorder affecting the thyroid are advised to avoid eating foods rich in iodine as well as iodine supplements. That’s because the gland uses iodine to make thyroid hormones and so, eating foods that contain large amounts of iodine may make the condition worse.

Research shows that excessive iodine intake can result in increased thyroid autoantibodies. While other studies have shown that a low selenium intake and low serum vitamin D levels increased the risk of autoimmune thyroid disorders.

Thyroid function can be improved by eating a healthy and varied diet. It is important to include calcium-rich foods into your diet as well as keeping vitamin D at adequate levels. For healthy bones, your body needs both nutrients with calcium only able to work effectively if there is enough vitamin D. Vitamin D also supports your immune system function. To get enough vitamin D you need to expose your skin to sunlight if this is not possible, then you will need to take supplements.

Exercise is beneficial for your overall health. Although there is no evidence that physical activity can improve the levels of thyroid hormones in the blood, it can help to control the symptoms associated with an over or underactive thyroid. For example, exercise can aid weight loss, support mental health by reducing the effects of depression or mood imbalances as well as improve the fitness of your heart and lungs.

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[1] Lab Tests Online UK. (2017). Thyroid Antibodies. Available at:

[2] British Thyroid Foundation. (2018). Your Thyroid Gland. Available at:

[3] Godlewska, M et al. (2019). Thyroid Peroxidase Revisited – What’s New? Horm Metab Res: 51(12), pp 765-769

[4] National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Hashimoto’s Disease. Available at:

[5] National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Graves; Disease. Available at:

[6] Foley, TP Jr. (1992). The Relationship Between Autoimmune Thyroid Disease and Iodine Intake: A Review. Endokrynol Pol: 43(Suppl 1), pp 53-69

[7] Mantana, A et al. (2017). Dietary Factors Associated with Plasma Thyroid Peroxidase and Thyroglobulin Antibodies. Nutrients: 9

[8] British Thyroid Foundation. (2020). Vitamin D and Thyroid Disease. Available at:

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This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.