As one of the important organs in the human body, the main physiological functions of the kidneys are: (1) generation of urine and excretion of metabolites. People every moment in the metabolism, this process will produce a lot of waste (such as urea, uric acid, etc.), the vast majority of waste through the glomerular filtration, renal tubular secretion or reabsorption, and ultimately the formation of urine out of the body. (2) Maintaining fluid balance and acid-base balance in the body. The kidneys can regulate the acid-base balance and maintain the stability of the internal environment by promoting acid excretion. (3) Endocrine function: secretion of renin, prostaglandins, kinins, erythropoietin, active vitamin D3, etc. Usually renal function tests include creatinine, uric acid and urea nitrogen, which are the most commonly used renal function tests. There are also urine β2-microglobulin, urine albumin, urine immunoglobulin G, urine secretory immunoglobulin A, urine specific gravity and urine osmolality available. For the elderly and thin people, it may be inaccurate to rely solely on the blood creatinine value to evaluate renal function, and some special calculations need to be performed to correct or use other indicators of renal function (e.g. eGFR). Normal human kidneys have a strong compensatory ability, and mild renal impairment may not cause an increase in blood creatinine. However, when blood creatinine is elevated, it suggests that kidney function is severely impaired. When renal function decreases, the use of certain drugs is restricted. For example, when renal eGFR is less than 30ml/min.kg, the use of most drugs is contraindicated. Therefore, the use of drugs need to be taken under the guidance of doctors or pharmacists in regular hospitals, and regular monitoring of renal function to guide the adjustment of drugs.