Plasma neutrophil gelatinase-associated lipocalin is an early biomarker for acute kidney injury in an adult ICU population

Abstract

Purpose: Neutrophil gelatinase-associated lipocalin (NGAL) is a useful marker for acute kidney injury (AKI), particularly when the timing of renal insult is known. However, its performance in an adult critical care setting has not been well described. We performed this study to estimate the diagnostic accuracy of plasma NGAL for early detection of AKI and need for renal replacement therapy (RRT) in an adult intensive care unit (ICU).

Methods: We enrolled 307 consecutive adult patients admitted to a general medical-surgical ICU; 301 were included in the final analysis. Serial blood samples were analyzed for plasma NGAL using a standardized clinical platform. The primary outcome was AKI, defined as an increase in creatinine of at least 50% from baseline or a reduction in urine output to <0.5 ml/kg/h for >6 h.

Results: Of 301 patients, 133 (44%) had AKI during their ICU stay. Plasma NGAL was a good diagnostic marker for AKI development within the next 48 h (area under ROC 0.78, 95% CI 0.65-0.90), and for RRT use (area under ROC 0.82, 95% CI 0.70-0.95). Peak plasma NGAL concentrations increased with worsening AKI severity (R = 0.554, P < 0.001).

Conclusions: Plasma NGAL is a useful early marker for AKI in a heterogeneous adult ICU population, in which the timing of renal insult is largely unknown. It allows the diagnosis of AKI up to 48 h prior to a clinical diagnosis based on AKI consensus definitions. Additionally, it predicts need for RRT and correlates with AKI severity. Early identification of high risk patients may allow potentially beneficial therapies to be initiated early in the disease process before irreversible injury occurs.

Fig. 1

Plasma NGAL values by timing of AKI. Values represent first plasma NGAL specimen. *P-value refers to comparison with Non-AKI group

Fig. 2

Mean plasmaNGAL concentrations at various timepoints in patients with (solid squares) and without (open squares) acute kidney injury (AKI). For AKI patients, the X-axis shows AKI Day. AKI Day 0 is the day in which the diagnosis of AKI was first made based on the RIFLE criteria. The green bar indicates the days when there is AKI. For non-AKI patients, the X-axis represents consecutive NGAL collection days. Patients who never developed AKI had comparatively lower plasma NGAL values without notable variation (P < 0.001 at each time point). Error bars are SEM

Fig. 3

Receiver operator characteristic (ROC) curve for plasma NGAL. The area under the ROC is 0.78 (95% CI 0.65–0.90), demonstrating a good performance for the diagnosis of AKI within the next 48 h