Peak time of plasma NGAL and serum creatinine. (A) Time points of the highest plasma neutrophil gelatinase-associated lipocalin (NGAL) and serum creatinine values in mild acute kidney injury (AKI) patients (n = 39). (B) Time lags of the peaks between plasma NGAL and serum creatinine in each AKI patient. Negative values indicate plasma NGAL started to decrease earlier than serum creatinine did. Serum creatinine started to decrease earlier than plasma NGAL in only 8 of 39 mild AKI patients (21%).