At present, the common thyroid diseases in endocrinology mainly include hyperthyroidism and hypothyroidism. As the pace of life increases, the pressure of life also increases, so the urban population suffers from thyroid diseases such as hyperthyroidism or hypothyroidism, the most important indicator to check whether it is hyperthyroidism or hypothyroidism is to check the function of the thyroid gland, but we may not understand the test, here to teach you how to look at the thyroid test in a scientific way. Scientific identification of commonly used indicators 1, serum total thyroid hormone (TT4), total triiodothyronine (TT3): indicators of stability, repeatability is good, but susceptible to the level of thyroid-binding globulin and its influence on factors. 2.Serum free thyroid hormone (FT4), free triiodothyronine (FT3): free hormone in the serum that is not bound to protein, and it can more accurately reflect the functional state of the thyroid gland than the TT3 and TT4 measurements. However, due to technical reasons, the stability of the results is not as good as that of TT4 and TT3. 3. Thyroid Stimulating Hormone (TSH), Sensitive Thyroid Stimulating Hormone (sTSH): TSH is secreted by the pituitary gland, which promotes the synthesis and secretion of thyroid hormones by the thyroid gland. The TSH measured after technical improvement and sensitivity enhancement of the measurement method is sensitive TSH (sTSH), and the sensitivity of sTSH is about 10 times higher than that of TSH. 4. Thyrotropin Receptor Antibody (TRAb), Thyroid Peroxidase Antibody (TPOAb), Thyroglobulin Antibody (TgAb), and Thyroid Microsomal Antibody (McAb): all are autoimmune antibodies of the thyroid gland, and reflect the autoimmune etiology of thyroid diseases. 5.Thyroglobulin(Tg)：Secreted by thyroid cells, elevated serum Tg can be seen in inflammation and damage of thyroid tissues as well as stimulation of TRAb and TSH. 6.Calcitonin(CT):secreted by parafollicular cells of thyroid gland, this hormone mainly regulates calcium and phosphorus metabolism, and it is an important sign of medullary thyroid carcinoma. Identify the significance of changes in test indexes 1, hyperthyroidism: usually refers to hyperthyroidism caused by autoimmune mechanism, the results of laboratory tests are: TT4, FT4, TT3, FT3 level increases, TSH, sTSH level decreases, and TRAb level increases. TRAb is also an indicator for determining the prognosis of hyperthyroidism and the discontinuation of antithyroid drugs. 2, hypothyroidism: that is, hypothyroidism, TSH, sTSH and TT4, FT4 is the first choice of the necessary indicators for the diagnosis of hypothyroidism. When primary hypothyroidism occurs, its TSH, sTSH level increases, TT4, FT4 level decreases, and reflects the severity of the disease; TT3, FT3 can be normal in the early stage of the disease, and decrease in the late stage. TPOAb, TgAb, McAb is positive, suggesting that the cause of the disease is chronic lymphocytic thyroiditis. Secondary hypothyroidism, TSH, sTSH and TT4, FT4 levels are reduced. 3.Chronic lymphocytic thyroiditis: also known as Hashimoto’s thyroiditis, early laboratory results may have the manifestation of hyperthyroidism, and in the late stage, it manifests as hypothyroidism. the potency of TPOAb, TgAb and McAb is persistently elevated, and the significance of TPOAb is more sure. 4.Medullary thyroid carcinoma: Calcitonin is obviously elevated. Calcitonin assay has special significance in the diagnosis of medullary thyroid cancer and monitoring of tumor recurrence after surgery. 5.Differentiated thyroid cancer: elevated thyroglobulin is a sensitive and specific indicator of incomplete treatment or recurrence, which is of great significance in monitoring the efficacy and recurrence. Thyroid examination can determine whether you are suffering from hyperthyroidism or hypothyroidism, and then according to the indicators of thyroid examination, you can also scientifically formulate the treatment program for hyperthyroidism or hypothyroidism.