Biochemical urea refers to checking urea nitrogen and creatinine, which requires blood sampling. In the blood biochemical examination program, it can indicate whether the kidney function is abnormal. If urea nitrogen and creatinine are significantly higher than normal, it indicates that there is renal function impairment, which can be seen in acute renal failure stage and chronic renal failure stage. If the primary disease is further clarified by urinary routine, liver function, glycosylated hemoglobin, urological ultrasound, PTH, ENA series, etc., active treatment will be carried out. If the patient is caused by acute renal failure, the cause can be found and then treatment such as kidney preservation, blood pressure and urine protein reduction can be carried out, and most patients can recover to normal. If caused by chronic renal failure, the aim of treatment is to slow down the progression of the disease and preserve residual kidney function. Aggressive renal replacement therapy, such as hemodialysis, peritoneal dialysis or kidney transplantation, is required in advanced stages.