Long-term outcome of hyperthyroidism diagnosed in childhood and adolescence: a single-centre experience

Background The objective of the study was to evaluate the long-term outcome of paediatric-onset hyperthyroidism with follow-up into adulthood and to identify any early predictors of a need for definitive therapy (DT). Methods In a retrospective analysis of patients diagnosed with hyperthyroidism under the age of 18 years and at follow-up, a comparison was made by categorising them into those who underwent definitive therapy (DT group), i.e. thyroidectomy/radioactive iodine (RAI), those who remained on antithyroid drugs (ATD) (CBZ group) and those who had complete remission (RE group). Results Sixty-one (49 females, 12 males) patients with a median age of 15.1 years (range: 3.6-18) at diagnosis were studied. The duration of the first course of ATD varied from <1 year (7%), 1-2 years (26%), >2 years (46%) and ATD never discontinued (21%). Disease relapsed in 69% of patients with <1 year of ATD vs. 79% with >2 years of ATD. At follow-up, the median duration since diagnosis was 8.75 years (range 2.0-20.7 years) and the median age at follow-up was 23.2 years (8-36 years). Thirty-three percent (20/61) had undergone DT (DT group) - with 16.5% (n=10) on RAI and 16.5% (n=10) on surgery, 36% (22/61) were on ATD (CBZ group), whilst 32% (19/61) had undergone full remission (RE group). The comparison did not identify any statistically significant difference for predictor factors at diagnosis including age, T4 and free T4 levels, thyroid peroxidise antibody levels (TPO) and the duration of the first course of carbimazole (CBZ) treatment. Conclusion Long-term complete remission of paediatric-onset hyperthyroidism in our study was 31%. There were no predictors identified that could help predict the long-term outcome, especially into adulthood.