Weight gain after treatment of Graves' disease in children.

OBJECTIVE: The frequency of and risk factors for weight gain in children treated for Graves' disease have not been described. We evaluated change in BMI-Z score and predictors of weight gain in this population.

DESIGN: Retrospective review of data from January 2000 to July 2011.

PATIENTS: Two hundred and twenty two children and adolescents with Graves' disease (ages 2-18 years) evaluated following radioactive iodine administration (RAI); (n = 101), thyroidectomy (n = 9) and initiation of medical therapy (n = 112).

MEASUREMENTS: Changes in body mass index Z score over 12 months (ΔBMI-Z0-12 ).

RESULTS: All treatment groups in each gender and race increased BMI-Z (median ΔBMI-Z0-12 was positive). T3 levels following RAI (P = .04) and weight lost at the time of administration (P = .02) in the RAI group and free T4 levels in the medical therapy group (P = .03) were positively correlated with ΔBMI-Z0-12 . Race was a significant predictor only in the medical therapy group (P = .01). Age negatively correlated with ΔBMI-Z0-12 in both the RAI (P < .001) and medical therapy groups (P = .003). Gender, maximum TSH in the 12 months after RAI and initial dose of LT4 replacement did not correlate with ΔBMI-Z0-12 . The prevalence of overweight and obesity in our cohort was similar to US children.

CONCLUSIONS: Weight gain during treatment for Graves' disease is common in children, and many children become overweight or obese during treatment. Risk factors include greater degree of hyperthyroidism at presentation and time of RAI and younger age. Weight lost upon presentation may also predict greater weight gain. Control of subsequent hypothyroidism does not appear to affect weight gain.