Creatinine is the result of the degradation of the creatine, component of muscles, it can be transformed into ATP, that is a source of high energy for the cells. The creatinine production depends on the modification of the muscular mass, and it varies little and the levels usually are very stable.Is excreted by the kidneys. With progressive renal insufficiency there is retention in blood of urea, creatinine and uric acid.Elevate creatinine level may be indicative of renal insufficiency.Clinical diagnosis should not be made on a single test result; it should integrate clinical and other laboratory data.