I. Patients who can choose iodine 131 treatment 1. Patients with diffuse enlargement of thyroid gland. 2. Patients with hyperthyroidism with abnormal liver function, leukopenia, thrombocytopenia, allergy to antithyroid drugs, relapse after antithyroid drug treatment, bone and joint pain after antithyroid drug treatment, hematocrit or abnormal liver function, relapse after surgery or those who do not want surgery. 3. Graves’ hyperthyroidism combined with chronic lymphocytic thyroiditis and increased iodine uptake rate. Iodine 131 therapy is contraindicated in the following cases: 1. Patients who are pregnant or breastfeeding. 2. Patients with acute myocardial infarction in the acute phase. 3. Patients with severe renal impairment.