Effects of Overweight on Risk of Thyroid Nodules in Children and Adolescents: The Fukushima Health Management Survey.

Context: Examining how overweight/obesity impacts thyroid nodule development in children and adolescents by sex and age allows speculation on the mechanism.

Objective: We examined whether overweight/obesity in children and adolescents is associated with thyroid nodule development by sex and age.

Methods: Approximately 300 000 participants who underwent thyroid ultrasonography in the Fukushima Health Management Survey after a nuclear accident were enrolled. Those without nodules in the initial 2 examinations (1-3 and 4-5 years postaccident) were prospectively assessed for nodule development in the third examination (6-7 years postaccident) relative to baseline overweight status, with an average follow-up of 4.2 years. This was a population-based prospective cohort study. The first and second thyroid examinations involved 299 939 and 237 691 participants, respectively, excluding those with thyroid nodules. After the third examination, 184 519 participants were finalized for analysis. Multivariable adjusted odds ratios of new detected thyroid nodules for overweight participants were compared with normal-weight participants.

Results: New thyroid nodules were detected in 660 participants. Being overweight was positively associated with thyroid nodules. The adjusted odds ratio (95% CI) of thyroid nodules for overweight participants compared with other participants was 1.27 (1.04-1.57). Additionally, the multivariable adjusted odds ratios for overweight males and females were 1.21 and 1.32, respectively, and those for different age groups (0-9, 10-14, and 15-19 years) ranged from 1.17 to 1.75.

Conclusion: Being overweight was associated with thyroid nodules in children and adolescents, mostly adolescent females, regardless of their proximity to the nuclear power plant.