Clinical Features and Remission Rate of Pediatric Graves’ Hyperthyroidism Treated With Antithyroid Drug

Introduction: Pediatric Graves’ hyperthyroidism needs long-term therapy and there is no specific guideline. Antithyroid medication is used as the first line of treatment, among antithyroid medication, radioiodine therapy, and surgery. The study was designed to investigate the clinical features and remission rate and the factors associated with the remission of Graves’ hyperthyroidism treated with antithyroid drug in children and adolescents. Methods: Initially, 114 children and adolescents who have been managed with thyrotoxicosis in a single tertiary center were included in the study. Retrospective review of medical records was performed on the demographic data, clinical information, and laboratory results. Ten patients with Hashitoxicosis, 36 patients who were followed less than 1 year, and 19 patients with no available initial results of thyroid function test were excluded from the study. We analyzed the clinical features and remission rate between the group with remission and the group without remission. Chi-square, Fisher’s exact test, and t-test were used for statistics. Results: A total of 49 patients were included in the study (M:F 11:38). Mean age at diagnosis was 12.6±3.7 years old and the follow up duration was 4.9±2.5 years. Goiter was visible in 47 patients (96%) and exophthalmos was found in 12 patients (24%). Thirteen patients (27%) showed treatment-related hypothyroidism during follow up. Twenty-seven patients (55%) could discontinue the medication for more than 1 month. Among those, eleven patients showed recurrence and 6 out of 11 patients reached remission again. As a result, 22 patients (45%, male 7) maintained the remission state. Average time till remission was 4.2±2.4 years. Remission rate was 2%, 8%, 12%, 35%, and 45% during the treatment of 1, 2, 3, 4, and 5 years, respectively. Mean follow up duration was significantly longer in the group with remission (5.7±2.2 years), compared with the group without remission (4.3±2.6 years) (p<0.05). There was no significant difference in the presence of goiter or exophthalmos between two groups (goiter 95.5% vs 96.3%; exophthalmos 18% vs. 30%). Incidence rate of hypothyroidism during treatment was also not statistically different between the groups (36% vs. 19%). Age at onset, recent age, initial levels of T3, free T4 or TSH, and the presence of anti-thyroglobulin antibody or anti-thyroid peroxidase antibody were not significantly different between the groups. In contrast, initial levels of TSH receptor antibody was significantly lower in the group with remission (15.6±9.7 IU/L vs. 26.2±14.7 IU/L, p=0.004). Conclusion: This study showed that the remission rate was 45% during the treatment duration of 5 years. Initial titer of TSH receptor antibody was the most important factor associated with the remission in the pediatric Graves’ hyperthyroidism.