If Iodine-131 treatment is needed after thyroid cancer surgery based on the pathology, it is recommended to do it 4-6 weeks after surgery. Because before doing iodine-131 treatment must be in the state of high TSH value, need to be greater than 30, before iodine-131 treatment to stop levothyroxine sodium tablets for 2-3 weeks, so that the value of TSH is greater than 30, which is more conducive to the uptake of iodine, the image is more obvious. At the same time, too early to do iodine-131 treatment may lead to parathyroid gland damage, because after the operation there may be a transient hypoparathyroidism, poor blood supply, and if the radiation treatment again, it may lead to permanent hypoparathyroidism, so it is not advisable to do it too early. Moreover, after iodine-131, a follow-up is needed in 4-6 months, the first time is nail clearance treatment, and if lesions are found, further clearance treatment will be performed after 4-6 months.