Kidney function refers to the function of the kidneys to excrete metabolic wastes from the body, maintain the stability of electrolytes in the body and acid-base balance. There are three main aspects of kidney function: first, the production of urine excretion of metabolic products. In the process of metabolism, the body produces many kinds of waste products, most of which are excreted in urine through glomerular filtration and tubular secretion. Second, maintain the balance of body fluids and acid-base balance in the body. Through glomerular filtration, tubular reabsorption and secretion, the kidney excretes excess water, regulates the acid-base balance and maintains a stable internal environment. Endocrine function. The kidney can secrete renin, prostaglandin and kinin to regulate blood pressure, as well as erythropoietin and active vitamin D.