Acut Kidney Injury (AKI) is the new term to describe an abrupt reduction in kidney function. AKI superseeds all other terms such as ARF. The last two of the RIFLE Classification (Risk of renal dysfunction; Injury to the kidney; Failure of kidney function; Loss of kidney function; and End-stage kidney diseas) actually represent outcome rather than stages and hence have been removed from the current classification of Acute Kidney Injury. There are 3 stages of AKI; each represents an increasing degree of renal impairment. Research for early markers of Kidney injury is on. Serum Creatinine (SCr) and Urine Output (UO) are not sensitive or specific indicators of AKI.