The dose of iodine 131 for hyperthyroidism needs to be decided according to the patient’s specific situation, usually the dose range is 2.59~4.44MBq per gram of thyroid tissue. 1. Calculated dose method: Iodine 131 treatment for hyperthyroidism is usually calculated based on the mass of the thyroid gland and the iodine uptake rate, and the usual dose range per gram of thyroid tissue is 2.59~4.44 MBq. Oral Iodine 131 Activity (MBq) = [Scheduled Amount (MBq/g) x Thyroid Mass (g)]/[Maximum RAIU or 24 h RAIU (%)]. 2. Semi-fixed measurement method: The semi-fixed dose method is based on the thyroid mass for calculation. For smaller thyroid, i.e., up to 30 g, the dose is usually 185 MBq; for medium-sized thyroid, i.e., 30-50 g, the dose is usually at 370 MBq; and for larger thyroid, i.e., up to 50 g, the dose is 555 MBq. 3. Fixed-metering method: Fixed-metering method is based on a fixed dose, which is usually 370~740MBq. This type of method is simpler and has a high remission rate, but is prone to hypothyroidism. Patients with hyperthyroidism who need iodine 131 treatment should actively cooperate with the doctor, and the specific dose should follow the doctor’s instructions.