Introduction:
The aim of the study was to confirm whether higher levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and N-acetyl--D-glucosaminidase (NAG) are associated with mortality risk scores in severe septic patients with acute kidney injury (AKI).

Material and methods:
A prospective observational study was performed in an adult critical care unit. A total of 135 patients were included. The levels of urinary NGAL, KIM-1 and NAG were compared between patients with acute physiology and chronic health evaluation (APACHE II) score > 25 (group A, n = 31) and APACHE II score ≤ 25 (group B, n = 104).

Results:
Median level of NGAL was 105.1 ng/ml (77.6–132.5) in group A versus 40.0 ng/ml (18.6–60.5) in group B (p < 0.001), KIM-1 was 16.2 ng/ml (10.2–22.3) versus 3.3 ng/ml (1.8–4.6) (p < 0.001), and NAG was 32.0 U/l (17.5–46.4) versus 15.0 U/l (7.7–22.3) (p < 0.001). The area under the receiver operating characteristic curve for NGAL was 0.70 (95% CI: 0.60–0.79), KIM-1 was 0.75 (95% CI: 0.66–0.83), and NAG was 0.69 (95% CI: 0.60–0.79). A NGAL level > 102.5 ng/ml had 95% sensitivity and 76% specificity, KIM-1 > 7.3 ng/ml had 96% sensitivity and 61% specificity, and NAG > 15.4 U/l had 86% sensitivity and 74% specificity.

Conclusions:
In severe septic AKI patients, high levels of NGAL, KIM-1 and NAG are associated with mortality risk scores. Urinary NGAL, KIM-1 and NAG concentrations higher than 102.5 ng/ml, 7.3 ng/ml and 15.4 U/l respectively may be used to predict increased of death risk scores.