To date,AKI diagnosis has been limited to observation of increasing levels of serum creatinine,decrease in urine output,and alterations in urinary chemistry (Bellomo.et al.2004;Mehta.et al. 2007) Nevertheless,serum creatinine levels do not increase significantly until renal function has decreased to 50% in addition,the level of serum creatinine may be affected by the patient's muscle mass,catabolic state,protein intake,weight,sex and tubular secretion of creatinine.Therefore,applying serum creatinine as a biomarker for diagnosing AKI may result in the loss of valuable time (Mishra.et al.2005;Sirota.et al.2011)