Multifaceted delineation of atrophic thyroiditis among pediatric population: An extensive literature survey

Autoimmune hypothyroidism is categorized into Hashimoto thyroiditis (HT) and atrophic thyroiditis (AT). Although a consensus exists among Japanese endocrinologists that pediatric AT is associated with severe hypothyroidism, the question remains whether AT and HT are separate conditions. To investigate the clinical characteristics of pediatric AT, we conducted a comprehensive literature review using PubMed and ICHUSHI, a local database. We identified 54 patients (43 females), diagnosed ≤ 18 yr of age, based on 19 English- and 28 Japanese-language publications; 45 patients were Japanese. The onset of the disease typically occurs before puberty. The patients exhibited severe hypothyroidism, with median TSH level of 518.8 μIU/mL (interquartile range [IQR]: 333.0-808.6) and median Free T4 level of 0.16 ng/dL (IQR: 0.08-0.40). Common findings included a low height SD score (median -2.54 SD), low height-velocity SD score (median -3.60 SD), body mass index +1 SD (40%), delayed bone age (64%), pericardial effusion (70%), and an enlarged pituitary gland (78%). Abnormal blood test results were frequently observed, including Hb (82%), CPK (83%), AST (94%), ALT (82%), and total cholesterol (95%). Ultrasound 3D volumetry, conducted for 14 thyroid lobes, revealed 13 lobes below the 25^th percentile. In conclusion, our study underscores the clinical presentation of pediatric AT, marked by severe hypothyroidism and a small thyroid gland. Nevertheless, the paucity of data on non-Japanese patients suggests a need for further research to determine if AT and HT are indeed distinct entities.