Plasma neutrophil gelatinase-associated lipocalin as an early biomarker for prediction of acute kidney injury after cardio-pulmonary bypass in pediatric cardiac surgery culture results [14], we further explored the rela- tionship between sepsis and NGAL. After excluding cases with AKI grades II and III, we compared two groups: the first one showing evidence of sepsis versus the second group with no evidence of sep- sis, as shown in Table IV. The difference between the groups was non-significant. Discussion Acute kidney injury, formerly known as acute renal failure, continues to represent a very common and potentially devastating problem in critically ill children [15, 16]. Unfortunately, the mortality and morbidity associated with AKI remain unacceptably high, with mortality rates approaching 80% in crit- ically ill children with multiple organ dysfunction syndrome [17]. The association between cardiopulmonary bypass and AKI is well recognized [18]. In current clinical practice, AKI is typically diagnosed by meas- uring an acute rise in serum creatinine. However, it is well known that creatinine is an unreliable and insensitive indicator during early, acute changes in kidney function, as serum creatinine concentrations typically do not change until approximately 50% of kidney function has already been lost [19]. In the present work, plasma NGAL mean levels were compared between group I (AKI grades II and III) and group II (no AKI and AKI grade I) (Table II). The results showed that there were high- ly significant differences in plasma NGAL levels between the groups; this significant difference start- ed as early as 2 h after surgery (p < 0.0001), which reflects the potential role of plasma NGAL as an ear- ly biomarker in predicting AKI. The same results have been confirmed in many studies [12, 20, 21]. The relationship between plasma NGAL and serum creatinine levels, as well as the correlations of each marker with AKI at different time intervals, were studied (Table III, Figure 1). Plasma NGAL levels were found to be signifi- cantly correlated with both serum creatinine and AKI at 2, 12 and 24 h after surgery, whereas serum creatinine did not show a significant correlation with AKI until after 12 h following surgery. Table III. Correlation of plasma NGAL with serum cre- atinine at 2, 12 and 24 h after surgery Serum creatinine [mg/dl] Plasma NGAL [ng/dl] 2 h after surgery 12 h after surgery 24 h after surgery *Highly significant correlation Value of r 0.4758 0.7194 0.8075 Value of p 0.0019 < 0.0001* < 0.0001* 1.0 0.8 fr0.6 o e u laV0.4 0.2 0.0 2 12 Time after surgery [h] 24 Plasma NGAL Serum creatinine Figure 1. Correlation coefficient (r) of plasma NGAL versus serum creatinine with acute kidney injury at varying time intervals (2, 12, and 24 h after surgery) NGAL – neutrophil gelatinase-associated lipocalin Many studies have explored the relationship between NGAL and AKI in children and adults. Zap- pitelli et al. [12], in a study on critically ill pediatric patients, found that NGAL concentrations in AKI patients exhibited a six-fold increase in concentra- tion that persisted from 48 h before to 48 h after development of AKI, and concluded that NGAL could serve well in predicting AKI before a rise in serum creatinine becomes apparent. In 2008, Devarajan [22] showed that plasma NGAL meas- urements could represent an early biomarker of AKI in the pediatric intensive care setting, being able to predict this complication about 2 days prior to the rise in serum creatinine with high sensitivity Before surgery 2 h after surgery 12 h after surgery 24 h after surgery Arch Med Sci 2, April / 2012 Table IV. Plasma NGAL mean levels in patients with sepsis versus patients without sepsis after excluding cases with AKI grades II and III Plasma NGAL [ng/dl] Group I Group II Value of p Evidence of sepsis (n = 12) No evidence of sepsis (n = 9) Mean 39.58 63.08 79.75 102.33 SD ±14.51 ±18.26 ±16.36 ±27.2 Mean 32.89 70 88.89 115.67 SD ±15.92 ±23.18 ±27.27 ±24.97 0.3281 0.4530 0.3501 0.2643 253