Creatinine is the product of the metabolism of human muscle tissue, there are many factors affecting creatinine, such as kidney disease, malnutrition, physical factors can affect creatinine.1, the factors of kidney disease, renal failure is the most important factor affecting creatinine, if the patient appears to have renal failure, the symptoms of creatinine elevation can occur, because of renal failure, creatinine and other toxins can not be discharged out of the body, so creatinine elevation occurs. 2, Malnutrition can cause the metabolic rate in the body to reduce, thus appearing symptoms such as creatinine reduction.3, physical factors, if the patient is physically thin and infrequent exercise, then its creatinine level is lower. If the patient is strong and loves to exercise, his metabolic rate will be high and his creatinine level may be high, but it will not exceed the normal value.