The endocrine system of the human body includes the pituitary gland in the brain, the thyroid and parathyroid glands in the neck, the thymus in the chest, the pancreas in the abdomen, and the adrenal glands in the kidneys, with the exception of the ovaries and testes. They are all important systems involved in the regulation of the body’s functions, and one cannot be without the other. The thyroid gland has the function of secreting thyroid hormone, which can promote the body’s metabolism. If the secretion of thyroid hormone is reduced, it will cause a decrease in protein synthesis, leading to poor brain and bone development and causing cretinism. The hormones secreted by the parathyroid glands have the function of promoting calcium and phosphorus metabolism in the body, and if they are secreted too much or too little, the corresponding clinical symptoms will appear. The role of insulin secreted by the pancreas on the human body is understood by many people. A congenital deficiency will cause type 1 diabetes, which requires lifelong insulin replacement therapy, otherwise it will cause many complications, and in serious cases, it will lead to the death of the patient.