Hyperthyroidism (or hyperthyroidism) is a relatively common endocrine disorder. It is caused by excessive secretion of thyroid hormones resulting in hyper-metabolism and disturbances of the vegetative nervous system. It can be divided into primary hyperthyroidism (diffuse enlargement of the thyroid gland with proptosis), secondary hyperthyroidism (nodular goiter with hyperthyroidism and no proptosis, but prone to myocardial damage), and hyperfunctioning adenoma, depending on the cause. Clinical manifestations of hyperthyroidism: hypersensitivity, agitation, palpitations, fatigue, tachycardia, weight loss, hyperphagia, fear of heat, excessive sweating, increased stool frequency, menstrual irregularities, etc. T3T4 is often elevated in laboratory tests. Sometimes T4 is normal but T3 is elevated, which is called T3 hyperthyroidism. Therefore, a normal serum T4 cannot exclude hyperthyroidism, and T3 must be measured at the same time.