Thyroiditis is a large group of diseases characterized by inflammation of the thyroid gland. Clinically, it is divided into several types according to the etiology and symptoms, and the prognosis varies from one type to another. By etiology: they can be classified as viral, bacterial, autoimmune, parasitic, post-radiation, tuberculosis, syphilis and AIDS infections. The most common clinical thyroiditis are chronic lymphocytic thyroiditis, subacute granulomatous thyroiditis, and painless thyroiditis. The most common from an etiologic point of view is autoimmune thyroiditis. According to the rapidity of onset: it can be divided into acute suppurative thyroiditis, subacute thyroiditis, and chronic thyroiditis. Subacute thyroiditis is further divided into subacute granulomatous thyroiditis, also known as subacute thyroiditis, and subacute lymphocytic thyroiditis (painless thyroiditis), which is further divided into sporadic thyroiditis and postpartum thyroiditis. In contrast, chronic thyroiditis includes chronic lymphocytic thyroiditis (Hashimoto’s thyroiditis) and chronic fibrotic thyroiditis. Most thyroiditis symptoms are similar, except for the painful enlargement caused by inflammation of the thyroid gland itself, which usually undergoes a transformation from hyperthyroidism to hypothyroidism. This is because the inflammation destroys the thyroid follicles, causing stored thyroid hormones to leak into the bloodstream and causing symptoms of hyperthyroidism. Since the destroyed follicles cannot continue to secrete, the deficiency of thyroid hormones can lead to hypothyroidism. In some types of thyroiditis, follicular function can be restored, but in others, it becomes lifelong hypothyroidism. However, acute septic thyroiditis, with its rapid onset and obvious symptoms, is a rare or rare inflammation of the thyroid gland, mostly seen in children, mostly due to abnormal development of the thyroid gland or complicated by other abnormalities of the neck, followed by secondary bacterial infection, with blood tests that are consistent with septic inflammatory changes, but with generally normal thyroid function. Therefore, thyroiditis is a large group of diseases with multiple etiologies, each type has its own etiology and pathogenesis, and treatment and prognosis varies.