Chronic lymphocytic thyroiditis in children, also known as Hashimoto’s thyroiditis, is one of the common causes of goiter in children in coastal areas and the most common cause of acquired hypothyroidism in children and adolescents, and its incidence is increasing day by day. The clinical data of 33 cases of children with chronic lymphocytic thyroiditis treated in our hospital from January 1998 to December 2005 are analyzed as follows. 1. Data and methods 1.1 Clinical data Among the 33 cases, 5 were male, 28 were female, 85% were female; age ranged from 6 to 14 years old, average 9.6 years old; duration of the disease ranged from 2 months to 3 years, average 8.9 months. 9 cases (27%) had hyperthyroidism, mainly fear of heat, excessive sweating, hyperphagia, chest palpitations, irritability, etc. 12 cases (36%) had hypothyroidism, mainly fear of cold, weakness, appetite, etc. The other 12 cases (36%) did not have any conscious symptoms. All cases had progressive diffuse enlargement of the thyroid gland, including 11 cases with degree I enlargement, 16 cases with degree II enlargement, and 6 cases with degree III enlargement, with soft texture of the thyroid gland and no nodules. 33 cases had positive serum anti-thyroglobulin antibody (TG-Ab) (49% to 80%, normal <30%) and anti-thyroid microsomal antibody (TM-Ab) (all positive). Ab) were positive (42%-67%, normal <15%). Serum triiodothyronine (T3) ranged from 0.12 to 5.6 ng/ml (normal 0.6 to 1.8 ng/m1), with 9 cases of increase and 12 cases of decrease. Total serum thyroxine (T4) ranged from 3.1 to 20.3~tg/dl (normal 5.3~l1.5~tg/d1), with an increase in 9 cases and a decrease in 12 cases. Thyrotropin (TSH) ranged from 0.03 to 100 mU/L (normal 0.34 to 5.6 mU/L), with an increase in 12 cases and a decrease in 9 cases. Ultrasound examination of the thyroid gland showed an increase in thyroid volume in all cases, and two of them had a heterogeneous echogenic structure, showing hypointense echogenic areas of different sizes. 1.2 Treatment and follow-up Nine children with hyperthyroidism were given oral tabazol tablets; 12 children with hypothyroidism were given oral thyroxine tablets. The drug dose was adjusted according to clinical symptoms and thyroid function. The asymptomatic patients were not given medication, and thyroid function was reviewed at regular follow-up visits. 23 children were followed up at regular outpatient visits for 0.5-5 years, mainly to observe thyroid function and thyroid size. The result was that the thyroid function became normal in 4 cases, the thyroid function was normal in 2 cases with no recurrence of symptoms for more than 1 year after stopping the medication, and hypothyroidism in 3 cases; 8 cases with normal thyroid function at the initial diagnosis were followed up, and 3 of them became hypothyroid; 18 cases with hypothyroidism were followed up, and 14 cases were followed up, and 7 of them had stopped the medication for 0.5 to 3 years without any abnormality. All children had varying degrees of reduction in goiter and 15 cases returned to normal; TG.Ab and TM-Ab decreased to normal in 13 cases, while the rest still fluctuated above the normal range. The pathogenesis of chronic lymphocytic thyroiditis in children is due to the dysfunction of suppressor T lymphocytes, and T helper cells interact with B lymphocytes to produce antibodies (TG.Ab and TM.Ab) against thyroid components, which in turn lead to thyroid cell destruction through antibody-dependent cell-mediated cytotoxicity and NK cell-mediated cytotoxicity. The incidence of TG. The incidence of the disease has increased in recent years and is more common in females aged 7 to 11 years and adolescents. The disease has a slow onset and strong positive serum TG.Ab and TM-Ab are important features. In our group of 33 children, mainly females, with an average age of 9.6 years, all had goiter and positive TG.Ab and TM.Ab, which met the diagnostic criteria for chronic lymphocytic thyroiditis. The typical enlarged thyroid gland in children with this disease has a hard rubbery texture with a granular and lobulated surface, whereas the soft texture of the enlarged thyroid gland in children with this disease may be related to the short duration of the disease and the low formation of fibrous tissue. Chronic lymphocytic thyroiditis in children may present as hyperthyroidism or hypothyroidism, or may only have an enlarged thyroid gland, which is often misdiagnosed as a simple goiter, so children with an enlarged thyroid gland should be checked for TG.AB and TM-AB for early diagnosis, regardless of whether they have symptoms. There is no specific treatment for chronic lymphocytic thyroiditis in children, but the current treatment aims to maintain normal thyroid function in children, so the treatment plan depends on the thyroid function. The disease is self-limiting and thyroid function will gradually improve or return to normal as the disease progresses. Therefore, follow-up is necessary to adjust the treatment plan according to the follow-up results to ensure normal growth and development of children.