Blood Cr is blood creatinine, and the normal range is 88-176 μmol/L. Blood creatinine is the metabolite of creatine in human body, and high concentration of blood creatinine is commonly seen in glomerular filtration hypoperfusion caused by various reasons, for example, in acute renal failure, the blood creatinine will be obviously increased, and it will appear to be progressively increased, which is one of the signs of acute renal function damage. In addition, in chronic renal failure, blood creatinine will also be significantly increased. The blood creatinine test can also determine whether the patient is prerenal oliguria or renal substantial oliguria. When organic renal failure, creatinine concentration often exceeds 200 μmol/L. However, if it is pre-renal oliguria, such as dehydration, heart failure, nephrotic syndrome and other causes of effective blood volume decline, creatinine concentration is usually not more than 200 μmol/L.