Necessary tests should be performed before 131 iodine treatment for hyperthyroidism, including checking blood routine, blood levels of thyroid hormones (such as T3, T4, TSH, etc.), thyroid 131 iodine uptake rate and thyroid imaging. This is not only to clarify the diagnosis, but also an important basis for physicians to determine the dose of 131 iodine treatment. In order to ensure the accuracy of the above tests and the best results of the treatment, the patient should refrain from using iodine-containing drugs (such as western iodine tablets, X-ray imaging, etc.) for 4 weeks, from eating iodine-containing foods (mainly seafood such as seaweed, nori, salted fish, etc.) for 3 weeks and from taking drugs for thyroid diseases for 2 weeks before the above tests and treatment (exceptions are made for special cases).