CRE is the medical term for blood creatinine, which is produced by muscle metabolism and generally produces 1mg of creatinine per 20g of muscle. Blood creatinine is the result from the blood test, it often reflects the kidney function, the early stage of kidney function damage creatinine is normal, after the middle and late stage creatinine will appear elevated, this is because the kidney has a strong compensatory capacity. When part of the kidney is damaged, another part of the residual kidney can complete the function and physiological needs of the kidney. Therefore, while checking the blood creatinine, we should also improve the endogenous creatinine clearance, urinary routine, 24hUP quantification and other related tests to comprehensively assess the function of the kidneys.