The similar diagnostic accuracy of plasma/serum NGAL (17.9 [95% CI, 6.0-53.7]/0.775 [95% CI, 0.679-0.869]) to that of urine NGAL (18.6 [95% CI, 7.2-48.4]/0.837 [95% CI, 0.762-0.906]) was also shown within 6 hours from the time of insult (if known) or 24-48 hours before the diagnosis of AKI if the time of insult was not known. The gene discussed is LCN2; the disease is acute kidney injury.