Many of the post-operative thyroid patients who are discharged from my clinic ask the most frequently when they come to the follow-up clinic: Doctor, look at my labs, some are high and some are low, it’s not good, right? Especially, many thyroid cancer patients are more nervous about the changes of these indicators. Today I will explain the meaning of thyroid function indicators in post-operative thyroid surgery and our standardized judgment method for all post-operative thyroid patients. For all thyroid surgery patients, we generally require that thyroid function be rechecked basically every month for the first six months to guide the dosage of eugenol, or thyroid tablets, after surgery. So what are the indicators of thyroid function? There are five main indicators: T3, T4, FT3, FT4 and TSH, the first four of which refer to the actual level of thyroid hormones in the human blood, i.e., they are secreted directly from the thyroid glands; TSH, on the other hand, is not, as it is a hormone secreted by the pituitary gland in the skull, which is an important hormone for the central regulation of thyroid function in the human body, which means that TSH is not actually secreted by the thyroid gland, but rather by the central hormone that acts on the thyroid cells. An increase in TSH means that the center thinks your thyroid is not active enough to meet your body’s needs, so the center increases TSH secretion, stimulating the thyroid cells to increase the secretion of the four thyroid hormones. Conversely, if TSH decreases, that means the center thinks your thyroid hormone levels are too high and you don’t need as much, so naturally it decreases TSH secretion. So in a way, this is also an automatic “market economy” institutionalized management of the body. It is beneficial to the body. Once we understand the significance of thyroid function indicators, we can interpret the test results in a more reasonable way. For patients with benign tumors who still have some of their glands, we want to give the remaining glands sufficient rest so that they do not become diseased due to rapid stimulation. Therefore, the appropriate amount of oral medication is given to keep the indicators, especially TSH, in the normal range, which both protects the remaining gland and provides thyroid hormone supplementation, saving us from the rapid decline of glandular hormones caused by the sudden surgical removal of most of the thyroid gland. For patients with malignant tumors, there is another difference. We require post-operative review of indicators to keep the four thyroid functions as normal as possible, but TSH levels need to be depressed to below 0.2, or at least below normal. The purpose of this is not only to supplement thyroid hormone, but also, and more importantly, to suppress central TSH secretion through high oral doses of the drug, so that the remaining thyroid gland, even the metastatic thyroid tissue, will not receive sufficient positive stimulation of TSH. On the other hand, this is an important means of controlling the progression of the disease.