The tubular filtration rate is the total amount of filtrate produced by the two kidneys per unit time, called glomerular filtration rate, and the normal value is about 120-125 ml/min. Glomerular filtration rate mainly reflects the ability of blood to form primary urine after passing through the glomerulus, while creatinine clearance is generally called endogenous creatinine clearance, and the pile refers to the kidney’s ability to filter creatinine. Creatinine is divided into endogenous creatinine and exogenous creatinine, which are small molecules that can pass through the glomerulus and are mostly not reabsorbed by the renal tubules. In endogenous creatinine can be influenced by our diet and muscle activity, but there are very few influencing factors, so after most of them we can use endogenous creatinine clearance instead of glomerular filtration rate, because endogenous creatinine clearance is very easy to test. The two are also similar in normal human blood, and the results are also very similar, so that we generally use endogenous creatinine clearance, instead of glomerular filtration rate in clinical practice.