Creatinine clearance can be used to determine the presence or absence of damage to glomerular function and the extent of its damage. Specifically, as follows: 1, in adults with endogenous creatinine clearance below 90 ml/min, it shows reduced glomerular filtration rate function; 2, if reduced to 89-60 ml/min for mild damage; 3, reduced to 59-30 ml/min for moderate damage; 4, reduced to below 30 ml/min for severe damage; 5, reduced to 15 ml/min for early end-stage renal insufficiency 6. <5ml/min is end-stage renal insufficiency, which is the end-stage uremic phase, and such patients should be treated with dialysis. Therefore, creatinine clearance is a test to determine whether there is damage to glomerular function and the degree of damage.