LCN2 and acute kidney injury: First, focusing on all patients with suspected Leptospirosis, AKI patients had significantly higher urine and plasma NGAL (uNGAL, pNGAL) than non-AKI patients on the 1st day of enrollment, uNGAL; AKI vs non-AKI 435.5 ng/ml (interquartile range (IQR) 918.6) vs 18.3 ng/ml (IQR 39.9), P < 0.001, pNGAL: AKI vs non-AKI 1,015 ng/ml (IQR 919.8) vs 124.0 ng/ml (IQR 166.0), P < 0.001 (Fig 2A and 2B).