The role played by the kidney in the human body is divided into the following three aspects: First, excretion of metabolites in the body, such as urea nitrogen, creatinine, uric acid, etc.. Second, it can play a role in maintaining the stability of the internal environment, acid-base balance, etc. For example, the distal renal tubules have the role of alkalinizing urine, and the proximal renal tubules have the role of reabsorption, which can play a vital role in acid-base metabolic balance, sodium, chloride, potassium and other metabolic regulation. If the patient has oliguria or even anuria, there will be obvious hyperkalemia, and when the urine volume is higher than 3000ml/24h, there will be obvious hyponatremia and hypochlorhydria, etc. Third, hormone regulation, renal cortex and renal medulla secrete glucocorticoids and salt corticoids respectively, which have obvious regulatory effects on blood pressure, blood sugar and erythropoietin.