Thyroiditis is a common disease in endocrinology. Thyroiditis refers to the inflammation of the thyroid gland, which can be divided into two types: bacterial inflammation and autoimmune inflammation. Clinically, thyroiditis can be categorized into three types: the first is called acute suppurative thyroiditis, the second is called subacute thyroiditis, and the third is called chronic thyroiditis. Acute thyroiditis is a bacterial infection and the pathogens can be either bacteria or viruses. It is generally induced by an upper respiratory infection, which may trigger a bacterial or viral infection in the thyroid. Subacute thyroiditis is not a bacterial infection but an immunological inflammatory infection. The third type, chronic thyroiditis, is also known as Hashimoto's disease. All three types of thyroiditis can be treated in the department of endocrinology.