Creatinine can be clinically divided into blood creatinine and urine creatinine. Blood creatinine is commonly used clinically in units of μmoI/L and mg/dL, and the conversion between the two is 1 mg/dL equals 88.4 μmoI/L. The normal value of blood creatinine is generally between 40-110 μmoI/L. The unit commonly used in clinical practice for urine creatinine is mmol/d or mg/d, and the normal value of urine creatinine is between 600-2000 mg/d. In the clinic, if there is an increase in blood creatinine or a decrease in urine creatinine, it often indicates renal insufficiency, and it is necessary to go to the hospital to improve a series of related tests to further clarify the diagnosis and clarify what is the cause of renal insufficiency.