In clinical practice, chronic renal insufficiency is divided into five stages according to the value of endogenous creatinine clearance. stage CKD1 is relatively the mildest, with endogenous creatinine clearance greater than or equal to 90 ml/min. stage CKD2 has endogenous creatinine clearance between 60-89 ml/min, stage CKD3 has endogenous creatinine clearance between 30-59 ml/min, and stage CKD4 has endogenous creatinine clearance between 15-29 ml/min. For patients with CKD5, it is equivalent to end-stage renal insufficiency, which is the most severe category, with an endogenous creatinine clearance of less than 15 ml/min. For patients with CKD stage 5, renal replacement therapy, such as hemodialysis, peritoneal dialysis or kidney transplantation, can be started.