TPO and Hashimoto thyroiditis: Hashimoto’s thyroiditis (HT), the most common autoimmune thyroid disorder, is marked by lymphocytic infiltration of the thyroid gland, progressive destruction of thyroid follicles, and the presence of circulating autoantibodies, particularly anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies [1,2].