What is thyroid perioxidase and thyroglobulin antibodies test why is it used?

TPO/TAb: Thyroid Perioxidase and Thyroglobulin antibodies found in Hashimoto's thyroiditis an autoimmune disease of the thyroid that is causing low thyroid function. Not all those who have antibodies , have low thyroid function. That should be tested as well. You are treated if thyroid function is low https://www.thyroid.org/hashimotos-thyroiditis/