Thyroid cancer is the most common tumor of the endocrine system. The incidence of thyroid cancer has increased significantly in recent years. Surgery has been the best treatment for thyroid cancer. Although most thyroid cancers are treated well after standardized surgery, with long or even non-life-threatening survival, there is still a possibility of recurrence and metastasis, just like other malignant tumors in the body. Follow-up interval In principle, lifelong follow-up should be conducted, generally every three months within the second year after surgery, at least every six months from the second year to the fifth year, and at least once a year after the fifth year, but of course, if treatment-related discomfort occurs, you should go to the hospital in time. Color ultrasound: Ultrasound examination is non-invasive, radiation-free and easy to operate, so it is often the preferred follow-up method after thyroid cancer surgery. Ultrasound examination can detect recurrent or metastatic lesions of thyroid cancer that cannot be felt by physical examination. Thyroid function: including T3, T4, TSH, etc. After partial or total thyroid removal surgery, thyroid function is often deficient (hypothyroidism), plus the need to take thyroxine tablets for a long time after surgery, which may lead to thyroid dysfunction, so thyroid function needs to be monitored regularly, and then medication should be adjusted according to the results of the examination. Thyroglobulin: Thyroglobulin is secreted by the thyroid tissue and a very small amount of thyroglobulin is normally released into the blood, with a normal value of <10μg/L. After total thyroidectomy, the thyroglobulin level may decrease or may not be measured, while an elevated thyroglobulin level should alert to tumor recurrence or metastasis. If thyroglobulin is less than 1μg/L, the chance of recurrence is very low. If it is between 1μg/L and 10μg/L, the chance of recurrence is about 20%, and if it is more than 10μg/L, the chance of recurrence is more than 60%. Therefore, after total thyroidectomy, dynamic monitoring of serum thyroglobulin can predict early recurrence and metastasis. Serum calcitonin: Calcitonin is also secreted by the thyroid tissue, and the amount of calcitonin in normal human serum is very small. When medullary thyroid cancer is present, the serum calcitonin level is significantly higher than normal. After surgical removal of medullary thyroid cancer, its serum level will drop rapidly. Therefore, postoperative monitoring of serum calcitonin is an effective method to monitor the treatment effect of medullary thyroid cancer and to detect recurrent or metastatic lesions at an early stage. In addition, chest X-ray, abdominal ultrasound, cranial MRI, whole-body bone scan, PET and other tests can also help to detect distant metastases. Follow-up medication After thyroid cancer surgery, you often need to take levothyroxine tablets (euthyroxine) for a long time, and the dosage of thyroxine tablets should be adjusted according to the TSH level. The serum TSH value should be checked every 2 to 3 months to control the TSH value between normal and mild hyperthyroidism.