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Thyroid peroxidase (TPO)

Produced in the thyroid, this enzyme helps to make the critical thyroid hormones T3 and T4. Levels of TPO in the body are tested by measuring the amount of TPO antibodies. High levels are a sign of possible Hashimoto’s disease, an autoimmune disorder that is a type of hypothyroidism in which the body isn’t able to produce enough thyroid hormone and often manifests as dryness in skin.