The most reliable index reflecting glomerular filtration function is glomerular filtration rate, which is often referred to as GFR. glomerular filtration rate refers to the amount of filtrate formed by both kidneys per unit time, and is generally around 125 ml/min in normal adults. However, because it is difficult to measure glomerular filtration rate clinically, endogenous creatinine clearance is often used instead of glomerular filtration rate to reflect the function of glomerular filtration, and the normal index of endogenous creatinine clearance is between 80-120ml/min. In addition, cystatin C is also used clinically to reflect the glomerular filtration function, because cystatin C is not affected by external factors such as age, weight and gender, so it is relatively stable and more sensitive.