Primary hyperthyroidism is hyperthyroidism caused by thyroid disease, as opposed to secondary hyperthyroidism. Hyperthyroidism, or hyperthyroidism for short, is a group of hypermetabolic syndromes caused by high concentrations of thyroid hormones in the blood for various reasons. According to the different causes of hyperthyroidism, it is mainly divided into the following types: I. Secondary hyperthyroidism, when the hypothalamus, pituitary disease, the pituitary gland secretion of thyroid stimulating hormone (also known as TSH) increased, TSH can promote the thyroid gland secretion of T3, T4, secondary hyperthyroidism, also known as pituitary hyperthyroidism. Therefore, secondary hyperthyroidism laboratory tests show that TSH is elevated and T3 and T4 are elevated. Second, primary hyperthyroidism, is due to thyroid disease caused by the thyroid gland secretion of T3, T4 increased, increased T3, T4 feedback inhibit the pituitary secretion of TSH, so that TSH secretion is reduced, so the primary hyperthyroidism laboratory test manifested as T3, T4 increased, TSH decreased.