Early predictive value of neutrophil gelatinase-associated lipocalin in adult ICU patients with acute kidney injury

Introduction

We investigated the early predictive value of plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) compared with serum creatinine in patients with acute kidney injury (AKI) in a heterogeneous adult ICU population. Previous studies display the excellent predictive value of urine NGAL for AKI in a pediatric ICU setting [1, 2].

Methods

A prospective cohort study was conducted, including 63 patients. After ICU admission, plasma and urine samples were collected at eight time points. NGAL measurements were performed using an ELISA. The difference between the increase in NGAL and the increase in serum creatinine was calculated in relation to the time point at which maximum AKI was reached (T = 0). AKI was defined according to Acute Kidney Injury Network definitions.

Results

Mean age (± SD) in years and APACHE II (± SD) scores for AKI I (n = 22), II (n = 21) and III patients (n = 20) were respectively (56 ± 18, 21 ± 7), (58 ± 19, 25 ± 8) and (63 ± 13, 27 ± 7). In AKI III patients, the difference between the increase in plasma NGAL and the increase in serum creatinine expressed as a percentage (95% CI) at 72, 48 and 24 hours prior to maximum AKI was 203% (-169 to 574), -10% (-221 to 830) and -25% (-205 to 155). For urine NGAL and serum creatinine the difference was respectively 584% (-603 to 1,770), 756% (12 to 1,499) and 726% (240 to 1,212). Figures 1 and 2 depict the increase in urine NGAL and serum creatinine separately and their difference in relation to T = 0. There was no positive difference in patients with AKI stages I and II for urine or plasma at any time point prior to maximum AKI.

Figure 1

Increase in urine NGAL and serum creatinine AKI III.

Figure 2

Increase difference between urine NGAL and serum creatinine AKI III.

Conclusion

NGAL is, compared with serum creatinine, an earlier predictor of AKI III, in a heterogeneous adult ICU population. Urine NGAL provides a larger and more sustained window of early prediction than plasma NGAL in patients with developing AKI III. The use of urine NGAL as an early predictive biomarker for AKI III is therefore promising in an adult heterogeneous ICU setting.