Does Whole-Blood Neutrophil Gelatinase-Associated Lipocalin Stratify Acute Kidney Injury in Critically Ill Patients?

Purpose. To analyse the capacity of whole-blood NGAL (wbNGAL) to stratify AKI in critically ill patients with and without sepsis. Methods. Whole-blood NGAL was measured with a point-of-care device at admission and 48 hours later in patients admitted to a general ICU. Patients were classified by the AKIN and KDIGO classifications at admission and 24 and 48 hours. We performed an ROC curve analysis. wbNGAL values at admission were compared in patients with sepsis and septic shock. Results. The study included 100 consecutively admitted patients (40 female) with mean age 59.1 +/- 17.8 years. Thirty-three patients presented AKI at admission, and 10 more developed it in the next 48h. Eighteen patients had AKI stage 3, 14 of them at admission. Nine patients required renal replacement therapy. According to KDIGO at admission, wbNGAL values were 78 mu g/L (60-187) in stage 0 (n=67), 263 mu g/L (89-314) in stage 1 (n=8), 484 mu g/L (333-708) in stage 2 (n=11), and 623 mu g/L (231-911) in stage 3 (n=14), p=0.0001 for trend. Ten patients did not complete 48 hours of study: 6 of 10 were discharged (initial wbNGAL 130 mu g/L (60-514)) and 4 died (773 mu g/L (311-1010)). The AUROC curve of wbNGAL to predict AKI was 0.838 (95% confidence interval 0.76-0.92, p=0.0001), with optimal cut-off value of 178 mu g/L (sensitivity 76.7%, specificity 78.9%, p<0.0001). At admission, twenty-nine patients had sepsis, of whom 20 were in septic shock. wbNGAL concentrations were 81 mu g/L (60-187) in patients without sepsis, 481 (247-687) in those with sepsis, and 623.5 mu g/L (361-798) in the subgroup of septic shock (p<0.0001). Conclusions. Whole-blood NGAL concentration at ICU admission was a good stratifier of AKI in critically ill patients. However, wbNGAL concentrations were higher in septic patients irrespective of AKI occurrence.