Subacute granulomatous thyroiditis is an inflammatory disease of the thyroid gland, first described in 1904 by deQuervain and also known as deQuervain’s thyroiditis and giant cell thyroiditis. It is common in women and is a self-limiting disease associated with viral infection. The etiology is unknown, but it is generally thought to be due to a viral infection, often preceded by an upper respiratory tract infection 1-3 weeks before the onset of the disease. Clinical manifestations and laboratory tests Most commonly seen in middle-aged women aged 20-50 years, 3-6 times more often in women than in men, with seasonal and regional onset. There are prodromal symptoms of upper respiratory tract infection 1-3 weeks before the onset of the disease. The typical clinical manifestations are divided into hyperthyroidism, transitional phase, hypothyroidism and recovery phase. 1. The hyperthyroidism phase is in the second to sixth week of the onset of the disease, and is the early stage of the disease. The nodules may be present. This is accompanied by general symptoms such as fever, malaise, and fatigue, sometimes with a temperature of 39 degrees or higher. Hyperthyroidism symptoms such as transient fever, palpitations, excessive sweating, and irritability may occur. 50% of the peaks usually occur within 1 week and last <2-4 weeks. On examination, there may be mild to moderate increase in leukocytes, marked increase in ESR, usually above 40mm/h, increase in T3 and T4, decrease in TSH, decrease in iodine uptake by the thyroid gland, and separation phenomenon. Ultrasound shows an enlarged thyroid gland with internal hypoechoic areas, localized pressure pain, blurred borders, sparse blood flow within the hypoechoic, and abundant peripheral blood supply. Isotope scans show image fragmentation or uneven visualization, sometimes with one lobe fragmented. Thyroid puncture biopsy has characteristic multinucleated giant cells or granuloma-like changes. In the transitional phase and hypothyroidism, the above abnormalities gradually diminish and are self-limiting, mostly lasting several weeks to several months, and some of them do not appear to be hypothyroid and go directly to the recovery phase. 3. During the recovery period, the clinical symptoms of patients improve, goiter and nodules disappear, and no sequelae remain. Very few become permanently hypothyroid. The whole course of the disease usually lasts 2-4 months, some last more than half a year, with an annual recurrence rate of 2%. In some patients, the lesion on one side is close to the recovery period, and then the lesion on the other side appears again, resulting in clinical manifestations and fluctuations of the lesion and prolonging the course of the disease. Diagnosis The diagnosis of this disease is mainly based on clinical manifestations and laboratory tests. The diagnosis can be made based on the patient's enlarged, painful and hard thyroid gland with systemic symptoms, history of upper respiratory tract infection before the onset of the disease, rapid blood sedimentation, high T3 and T4 and reduced iodine uptake by the thyroid gland. The diagnosis is further supported by the presence of giant cells and granulomatous changes on thyroid puncture biopsy. Prevention and prognosis The prognosis is good and the course of the disease is self-limiting, but can recur. Strengthening resistance and avoiding upper respiratory tract infections and pharyngitis can help prevent the development of the disease. After recovery of thyroid function, follicular storage iodine function is restored more than 1 year after complete clinical remission, and the incidence of permanent hypothyroidism is <10%.