Value of plasma neutrophil gelatinase-associated lipocalin (NGAL) in distinguishing between acute kidney injury (AKI) and chronic kidney disease (CKD)

OBJECTIVE: In this study, we aimed to determine whether plasma NGAL levels could be used as a biomarker for distinguishing between AKI and CKD in emergency medicine. MATERIALS AND METHODS: This prospective study was conducted at the ED of a training and research hospital over a six-month period in 2015. Three groups were defined: an AKI group – defined as a new onset of at least a 1.5-fold or ≥0.3 mg increment increase of SCr values from the normal baseline, a stable CKD group – only included presence of stages 2 through 4 of CKD according to the National Kidney Foundation's KDIGO 2012, and a control group. After the initial evaluation of patients, venous blood samples were taken for routine biochemical, counter blood cell, and plasma NGAL measurement at admission. RESULTS: A total of 25 patients with AKI, 22 patients with stable CKD, and 22 control subjects were enrolled. Level of plasma NGAL in AKI group was higher than those of the stable CKD group (median: 794 ng/ml IQR: 317–1300 & 390 ng/ml IQR: 219–664, p < 0.001). AUC was measured as 0.68 (p = 0.02, 95% CIs: 0.54–0.84) to assess the utility of plasma NGAL levels at varying cut-off values for distinguishing between AKI and CKD. For plasma NGAL, the best cut-off level was found to be 457 ng/ml (sensitivity: 72.0%, specificity: 64%). CONCLUSION: This study has clearly demonstrated that plasma NGAL levels were higher in AKI patients than in CKD patients. However, in clinical practice, the use of plasma NGAL levels to distinguish between AKI and CKD is limited.