The investigators hypothesize that 131I is an effective therapy for children with Graves' Disease (GD) and will not be associated with long-term cancer risks when used in older children, but may be associated with excessive levels of whole body radiation in young children. To address issues of 131I safety and cancer risk in the pediatric population, the investigators propose to: (1) Perform dosimetry to assess whole body radiation exposure following 131I therapy in children treated for GD (2) the investigators will assess chromosome translocation as related to age and dose of 131I.

It is anticipated that these studies will provide new insights into RIA use in children and provide important information about radiation exposure associated 131I use in children. As such, these studies are expected to result in new recommendations for 131I use in the treatment of pediatric GD.