Hashimoto's thyroiditis is an autoimmune thyroiditis where the body itself has autoantibodies that lead to the destruction of thyroid follicular cells, resulting in the failure of thyroid cells. Therefore, Hashimoto's thyroiditis can manifest as hyperthyroidism, euthyroidism, and hypothyroidism. Ultimately, Hashimoto's thyroiditis may develop into hypothyroidism. Hypothyroidism is proliferative and generally cannot be completely cured, but clinical remission can be achieved through oral administration of levothyroxine. However, Hashimoto's thyroiditis cannot be completely cured and requires lifelong replacement therapy.