The role of the FT3/FT4 ratio in predicting remission and relapse in pediatric Graves’ disease

Long-term antithyroid drug (ATD) therapy is often required in pediatric Graves’ disease, yet adherence can be challenging. Therefore, identifying reliable predictors of remission and relapse is crucial for optimizing disease management. This study aimed to evaluate the role of the baseline FT3/FT4 ratio in predicting remission and relapse, alongside other potential markers, including TRAb levels, thyroid volume, and body mass index (BMI). This retrospective, single-center study included pediatric patients diagnosed with Graves’ disease and treated with ATDs. Age, sex, BMI, thyroid volume, TRAb, FT3, and FT4 levels were recorded at diagnosis, and the FT3/FT4 ratio was calculated. Remission was defined as maintaining euthyroidism for at least 12 months after discontinuation of ATD therapy, whereas relapse was defined as the recurrence of hyperthyroidism following remission. A total of 55 patients were evaluated. The remission rate was 43.6%, and among those who achieved remission, the relapse rate was 8.3%. No significant association was found between remission and age, sex, BMI, ATD duration, or the FT3/FT4 ratio. However, remission was significantly more likely in patients with TRAb levels < 10 IU/L (p < 0.05). Additionally, an inverse relationship was observed between thyroid volume and the likelihood of remission. Although the baseline FT3/FT4 ratio did not predict remission, it was significantly higher in patients who experienced relapse. An FT3/FT4 ratio > 0.54 pmol/pmol predicted relapse with 75% sensitivity and 98% specificity (AUC = 0.842; p = 0.048).

Conclusion: The baseline FT3/FT4 ratio demonstrated limited value in predicting remission but proved to be a strong indicator of relapse risk in pediatric Graves’ disease. Additionally, lower TRAb levels (< 10 IU/L) and smaller thyroid volumes were associated with higher remission rates. Together, these findings suggest that incorporating the FT3/FT4 ratio, TRAb levels, and thyroid volume into routine assessment may enhance risk stratification and support more personalized treatment approaches for pediatric Graves’ disease.