Creatine (C4H9N3O2) - methylguanosine acid. In humans, the greatest number of creatine is contained in striated muscles. Is creatine is the ability to attach phosphoric acid reaction pererozpodilyatysya. The resulting fosfokreatina serves as a reserve of high energy phosphate used in many biochemical reactions that require energy. The splitting of phosphocreatine is formed creatinine. The ratio of the number of creatinine allocated person with urine per day (in milligrams)to body weight in kilograms is called creatinine coefficient. In norm at men it is 20-26, women 14-22. The selection of creatine in the urine (see Creatinuria) may have diagnostic value, indicating a disease of the skeletal muscles.