Radiation-induced thyroiditis is a form of painful, acute thyroiditis resulting from radioactive therapy to treat hyperthyroidism or from radiation to treat head and neck cancer or lymphoma. It affects 1% of those who have received radioactive iodine (I-131) therapy for Graves' Disease, typically presenting between 5 and 10 days after the procedure.^[1] Stored T₃ and T₄ are released as rapid destruction of thyroid tissue occurs which results in pain, tenderness, and exacerbation of hyperthyroidism. ^{[citation needed]}