Epidemiological Study on the Incidence of Chronic Lymphocytic Thyroiditis in Childhood

An epidemiological survey on the incidence of chronic lymphocytic thyroiditis in childhood was performed in 11,353 apparently healthy school children in Chiba prefecture, Japan. The present study included 9,416 school children (4,401 boys and 5,015 girls, ages 6--18 yrs) in Chiba City and 1,937 children (744 boys and 1,193 girls, ages 16-18 yrs) in Tateyama City. The first group was selected as a representative of urban area, and the second group was selected as that of seaside area. Children having goiter were selected for testing antihyroblobulin and antimicrosomal antibodies in sera. Final diagnosis of chronic lymphocytic thyroiditis was based on histological specimens obtained by needle biopsies on the antithyroid antibody positive subjects. The overall incidence of chronic lymphocytic thyroiditis in these children with 1.7 per 1,000 children. There was a considerable sex difference in the prevalence. None of the patients were boys. In girls the incidence increased with age: ages 6-12 0.9, ages 13-15 4.6 and ages 16-18 3.1-4.2 per 1,000, respectively. The incidence in the seaside area, 2.6 per 1,000 was not significantly higher than that in the urban area, 1.8 per 1,000. Histologically, all cases were classified as focal thyroiditis.