1. Thyroglobulin measurement: TG value >10ng/ml is abnormal, such as simple goiter, all can find elevated serum TG, so TG cannot be used as a tumor marker for qualitative diagnosis, or although there is a residual thyroid gland, but the thyroid gland no longer exists after 131I treatment, there should no longer be TG, if TG is found to be elevated by radioimmunoassay, it indicates that there may be recurrence or metastasis of thyroid cancer in the body. TG can be used as a more specific tumor marker for postoperative dynamic monitoring to understand whether there is recurrence or metastasis of thyroid cancer in the body, and if there is still residual thyroid gland, the detection of TG can only be used as a reference, but not as useful as the former, so as not to interfere with the examination results. Calcitonin measurement: The level of calcitonin in normal human serum and thyroid tissue is very small, the level of radioimmunoassay calcitonin is 0.1~0.2ng/ml, most of them are >50ng/ml, and a significant increase of serum calcitonin is positive, but there is no such reaction in normal people, but the regulatory effect of calcitonin on blood calcium level is much less powerful than that of parathyroid hormone, so the serum calcium level is mostly normal, and the patient has no bone If serum calcitonin returns to normal, it means that the tumor is completely removed; if serum calcitonin is still high, it means that there is still tumor residue or metastasis has occurred, which helps to detect tumor recurrence early, improve treatment effect and increase survival rate. 3. Thyroid function test: All thyroid cancer patients should undergo thyroid function test, including plasma PBI and serum T3.