Discontinue iodine-containing foods and drugs: 1. kelp, agar, carrageenan, Lugol’s liquid, iodine-containing herbs for 2-3 weeks; 2. iodine-containing multivitamins for 7-10 days; 3. iodine for surgical skin disinfection for 2-3 weeks; 4. iodine-enhanced contrast agents for intravenous use for 6-8 weeks; 5. amiodarone for 3-6 months. Discontinuation of antithyroid drugs: 1. methimazole for more than 3 days; 2. propylthiouracil for more than 2 weeks; women of childbearing age should exclude pregnancy before 131I treatment.