F.I. Fadel, A.M.O. Abdel Rahman, M. Farouk Mohamed, S.A. Habib, M.H. Ibrahim, Z.S. Sleem, H.M. Bazaraa, M.M.A. Soliman and area under the curve (AUC) values of 0.68-0.78. The 2-h post-operative plasma NGAL levels strong- ly correlated with the duration and severity of AKI and length of hospital stay. Figure 1 shows the trend of both biomarkers in relation to AKI. Whereas plasma NGAL showed a rapid early rise 2 h after surgery which persisted until 12 h after surgery, with a slow decline there- after, serum creatinine showed a slow rise which was non-significant at 2 h but started to be significant at 12 h, with a further rise at 24 h after surgery. These recorded results reflect the nature of both biomarkers. Regarding serum creatinine, it took time to build up and that is why it became signifi- cant as time passed. On the other hand, plasma NGAL pumped up its level early when AKI devel- oped, which is why it was gradually washed out of the blood stream [23]. In order to explore the sensitivity and specifici- ty of plasma NGAL level in predicting AKI grade II and III (RIFLE: Injury and Failure), several cut-off val- ues were analyzed. Plasma NGAL level of 100 ng/ml at 2 h after surgery and 125 ng/ml at 12 h after sur- gery both recorded the highest accuracy, being 95% accurate. The sensitivity and specificity of plasma NGAL cut-off value of 100 ng/ml at 2 h after sur- gery were 100% and 90.48% respectively, while the sensitivity and specificity of plasma NGAL cut-off value of 125 ng/ml at 12 h after surgery were 89.47% and 100% respectively. The previous results show that plasma NGAL lev- el could be used for detection of AKI as early as 2 h post-operatively and to confirm AKI at 12 h with great accuracy and high sensitivity and specificity. Our results were close to a collective data analy- sis done in 2008 for some published performanc- es of NGAL as a predictive biomarker for AKI, which revealed mean AUC-ROC of 0.82; the mean derived sensitivity and specificity from these studies were in the 75-80% range [21, 22]. From the published studies, the derived optimal cut-off value of NGAL for the early prediction of AKI appeared to be at a median value of approximately 150 ng/ml [22]. Finally, the current study showed that sepsis was significantly evident in patients with AKI. Hence, we concluded that sepsis is a potential risk factor for developing AKI. Previous studies have mentioned that plasma NGAL levels might be affected by sep- sis [24, 25]. In a study by Bagshaw et al. [26], criti- cally ill patients with septic AKI were associated with significantly higher plasma NGAL at enrollment compared with non-septic AKI. 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