Understanding Anti TPO Antibodies
Thyroid disease is a common disorder. Screening tests for thyroid disease consists of measurements of anti-thyroid peroxidase (anti-TPO) antibodies, thyroid stimulating hormone (TSH) levels and levels of thyroid hormones (T3 and T4) in the blood. Anti-TPO antibodies indicate an autoimmune reaction in which the body sends immune cells to attack the thyroid gland. This attack can lead to thyroid diseases such as Hashimoto's thyroiditis, Grave's disease or postpartum thyroiditis.-
Thyroid Peroxidase
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Thyroid peroxidase (TPO) is an enzyme needed to produce thyroid hormones. The TPO enzyme helps the reaction which adds iodine to thyroglobulin, a protein necessary to producing the thyroid hormones. TPO function is stimulated by TSH. TSH is released by the pituitary in response to the body's need for more thyroid hormones, which are major hormones necessary for the body cells metabolism. Anti-TPO antibodies target the TPO enzymes slowing or stopping this necessary activity.
Significance
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Having anti-TPO antibodies does not necessarily mean one has thyroid disease. It can also indicate a chronic inflammatory disease, like rheumatoid arthritis, is present. People with Addison's disease (low adrenal gland hormones), celiac disease (gluten intolerance) or alopecia areata (an autoimmune reaction which causes baldness) can also have anti-TPO antibodies. However, from 5 to 50 percent of people with these conditions can also have a concurrent autoimmune thyroid disorder.
Antibodies in Autoimmune Disease
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The majority of thyroid disorders are caused by an autoimmune disease. Antibodies, or large proteins, normally attack foreign substances in the body like bacteria, viruses and toxins. Environmental or genetic disorders can turn the antibodies against the body. Anti-TPO antibodies target the TPO proteins hindering their function in the thyroid gland.
Thyroid Disease
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Anti-TPO antibodies are found in 75 percent of people with Graves disease. Graves disease leads to an over activity of the thyroid gland, or hyperthyroidism. It is most common in women over the age of 20. Anti- TPO antibodies are also found in 90 percent of people with Hashimoto's thyroiditis. This is a chronic inflammation of the thyroid gland which usually results in hypothyroidism or low function. It is most commonly found in middle-aged to elderly women. It also tends to be a disease clustered in families.
Postpartum Thyroiditis
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Pregnant women who have anti-TPO antibodies are at a high risk of developing postpartum thyroiditis. From 5 to 10 percent of pregnant women develop postpartum thyroiditis. This disease is characterized by hyperthyroidism followed by hypothyroidism. This can occur anywhere from 1 to 4 months after delivery. Women with other autoimmune diseases, a history of thyroid disorders or a family history of thyroid disease should be screened for anti-TPO antibodies during their pregnancy.
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