TPO and Hashimoto thyroiditis: Hashimoto thyroiditis is a typical T-cell-mediated autoimmune disease and is characterised by formation of tertiary lymphoid follicles within the thyroid (containing T-cells, increased Th1, and B cells), with the destruction of thyroid follicular cells generating hypofunction and the presence of anti-TPO and/or anti-Tg antibodies in the serum.