The utility of neutrophil gelatinase-associated Lipocalin (NGAL) as a marker of acute kidney injury (AKI) in critically ill patients

In current clinical practice, Serum Creatinine (SCr) is a commonly used marker for the diagnosis of acute kidney injury (AKI). Unfortunately, due to a delayed increase in SCr, it is unable to accurately estimate the timing of the injury. The purpose of this study was to assess the ability of plasma neutrophil gelatinase-associated lipocalin (pNGAL) to predict AKI in critically ill adult patients. The study was conducted at the Section of Chemical Pathology, Department of Pathology& Laboratory Medicine in collaboration with Department of Anesthesiology, at Aga Khan University Hospital in Karachi, Pakistan. Subjects in the age groups of18 to 60, that were admitted into the intensive care unit (ICU) with suspected sepsis were enrolled in this study.AKI was labeled by using Risk-Injury-Failure-loss-End Stage (RIFLE) criteria. Forty-eight patients, mean age being 46.5 ± 16.3, were recruited over a nine-month period. Multiple blood samples were collected from each patient at 12 h, 24 h, and 48 h. A total of 52.1% (n = 24) of ICU patients suspected of sepsis had developed AKI. Baseline characteristics of subjects with AKI were compared to those without AKI. Statistically significant difference was noted in gender (p-value< 0.05) and pNGAL (p-value< 0.001). However, no significant differences were seen with respect to age, in patients with and without AKI. The area under the curve (AUC) at12hr was 0.82 (95% CI 0.68-0.96) with a sensitivity of 70.8% and specificity of 90.9%.While AUCs at 24 h was 0.86(95% CI 0.74-0.97) with a sensitivity of 78.5% and specificity of 88.8%. Furthermore, there was a positive correlation between pNGAL and the length of ICU stay (r = 0.98). Non-survivors or expired patients had higher median pNGAL170 (202-117) ng/ml as compared to survivors 123(170-91) ng/ml. In conclusion, pNGAL is an early predictor of AKI in a heterogeneous adult ICU population. Plasma NGAL allows the diagnosis of AKI 48 h prior to a clinical diagnosis based on RIFLE criteria. Early identification of high-risk AKI in patients may allow earlier initiation of therapies and improve patient outcome.