The kidney has three basic functions, including: 1, the production of urine, excretion of metabolites: the body in the process of metabolism produces a variety of waste, the vast majority of waste through glomerular blood filtration, renal tubular secretion, with urine out of the body, that is, the kidney is the organ of detoxification; 2, maintain the balance of body fluids and acid-base balance in the body: the kidney through the glomerular filtration, renal tubular reabsorption and secretion function, excretion of body Endocrine function: the kidney can secrete renin, prostaglandin and kinin, and regulate blood pressure through renin-angiotensin-aldosterone system and kinin-bradykinin-prostaglandin system. In addition to this, it is also able to produce erythropoietin, which stimulates bone marrow hematopoiesis. Also the kidney is the site of degradation of many endocrine hormones, such as insulin and gastrointestinal hormones.