Summary
Thyroiditis consists of a number of different inflammatory processes in thyroid and is caused by a variety of factors. Among the various inflammatory thyroid lesions, Hashimoto’s thyroiditis is the most common, and we will focus on the mechanisms involved in this disease. While extensive studies have been performed to elucidate the immunopathogenesis of Hashimoto’s thyroiditis, the processes underlying this disease are still not fully understood. However, significant progress has been made in areas related to the roles that iodine, CD4+CD25+ regulatory T cells, and apoptosis play in autoimmune-mediated thyroid damage, the defining feature of Hashimoto’s thyroiditis.