After iodine 131, it is found that there is still residual thyroid gland, it may be necessary to have iodine 131 treatment again, and it is recommended to have the treatment under the guidance of the doctor. Thyroid iodine 131 treatment, which is clinically mainly used to kill residual thyroid tissues by radiation, can be used for hyperthyroidism and thyroid malignant tumors after resection surgery. If after iodine 131 treatment, patients experience fatigue, drowsiness, weight gain, chills, convulsions, increased menstrual flow and constipation in young and middle-aged women, it suggests that there is a possibility of early-onset hypothyroidism, and they should be followed up for review in a timely manner. For patients who are not cured or have poor therapeutic effect after 3-6 months of iodine 131 treatment, according to the needs of the condition, we can consider to carry out iodine 131 treatment again, and it is recommended to have an interval of 3-6 months with the initial treatment. After the second treatment, the patients should be followed up to observe the imaging performance and check the function of thyroid gland, so as to formulate reasonable treatment measures. For iodine 131 radiotherapy, consult the endocrinology department of a regular hospital.