Subacute thyroiditis, also known as viral thyroiditis, DeQuervain’s thyroiditis, granulomatous thyroiditis or giant cell thyroiditis, was first reported by DeQuervain in 1904. The disease has been increasing in recent years, with complex clinical changes, which can be misdiagnosed and missed, and is prone to recurrence, leading to a decline in health, but most patients can be cured. There is a reported tendency for seasonal onset of the disease and regional clustering of the disease. The disease is less common clinically, and a number of mild patients may be misdiagnosed as pharyngitis, with an estimated minority of atypical and undetectable clinical presentations. The disease is three to six times more common in women than in men. The age of prevalence is between 30 and 50 years. It is rare in children. (a) How to diagnose subacute thyroiditis 1. Painful and enlarged thyroid gland after recent viral infection, which may be accompanied by hyperthyroidism or episodic symptoms. 2. Diffuse or asymmetric mild to moderate enlargement of the thyroid gland with tenderness. 3. In the early stage, serum TT3, TT4, FT3 and FT4 may be elevated, TSH may be decreased, and TG-Ab and TPO-Ab may be positive in some patients. In the later stage, due to the destruction of thyroid tissue, serum thyroid hormone level may be reduced and TSH may be increased in a few patients. 4. Blood sedimentation is significantly increased, and white blood cell count is usually normal or mildly to moderately elevated. (B) How to treat subacute thyroiditis 1. There are various therapeutic measures for subacute thyroiditis, including thioureas, thyroid stimulating hormones and inhibitors of the amount of thyroid hormone. The evidence that the use of these drugs affects the disease process is not yet agreeable. There is no specific treatment for this disease. Treatment consists of two aspects: reduction of local symptoms and targeting abnormal thyroid function effects. In general, symptomatic management alone is sufficient for most patients. 2. For patients with hypothyroidism, replacement therapy with thyroxine tablets may be used to reduce the local enlargement of the thyroid gland. 3. Adrenal corticosteroids such as prednisone can be added when symptoms are severe. It has significant effect on the disease. Fever and thyroid pain can be rapidly relieved within 1 to 2 days of medication, and the thyroid gland often shrinks significantly after a week. The dose is: 5-10mg 4 times a day for 1 to 2 weeks, and then gradually reduce the dose for 1 to 2 months. If there is a relapse after discontinuation, prednisone can be used again, and thyroxine tablets can be added, especially for those with hypothyroidism. Levothyroxine 100-150ug or thyroxine tablets 80-120mg per day can be used in divided doses. After a few months, gradually reduce the dosage to stop the drug. 4. Analgesic and antipyretic drugs, such as anti-inflammatory pain, are also effective for this disease. Antibacterial drugs are not effective.