NGAL level was higher in non-survivors compared with survivors and was identified as an independent predictor of 28-day mortality. At RRT initiation, an optimal cutoff value of greater than 360 ng/mL had a sensitivity of 82.1% and a specificity of 59.2% for 28-day mortality. However, serum NGAL levels were not associated with renal recovery, ventilation-free days, or ICU-free days at 28 days.