Urinary NGAL levels in Stage 3 AKI patients (163.8 ± 21.1 μg/L) were significantly higher than those in Stage 2 AKI patients (146.1 ± 22.9 μg/L), and urinary NGAL levels in Stage 2 AKI patients were significantly higher than those in Stage 1 AKI patients (124.7 ± 18.8 μg/L); all differences were statistically significant (p < 0.01). The gene discussed is LCN2; the disease is acute kidney injury.