Creatinine has no effect on human body, but it is harmful to human body if the level of creatinine is too high. Creatinine is the product of muscle metabolism, generally every 20g muscle metabolism produces about 1mg of creatinine, creatinine through glomerular filtration out of the body, it is a metabolite, in the human body belongs to a kind of small molecule toxin, creatinine level higher represents the higher level of toxin, so it is harmful to the human body instead. If the kidney function is abnormal, the patient’s blood creatinine will rise. If the patient is malnourished, the muscle intake is too low, resulting in the reduction of muscle metabolites, creatinine level will be reduced accordingly, therefore, one of the indicators for checking renal function in the clinic is creatinine.