Thyroid Storm in a Child following Radioactive Iodine (RAI) Therapy: A Consequence of RAI Versus Withdrawal of Antithyroid Medication

A 7.5-yr-old boy with Graves' disease, difficult to control with antithyroid medication and radioactive iodine (RAI) therapy, developed thyroid storm encephalopathy on day 13 after withdrawal of methimazole therapy, 4 days after iodine-131 treatment. We attributed his thyroid storm to withdrawal of antithyroid medication as opposed to RAI therapy. We interpret this case as indicating that there may be a need to reevaluate the duration of antithyroid medication withdrawal before RAI therapy for hyperthyroid children at increased risk for thyroid storm.