Introduction
Neutrophil gelatinase-associated lipocalin (NGAL) predicts the development of acute kidney injury (AKI) amongst critically ill patients [1]. Serum and urinary NGAL have been shown to be elevated in patients with SIRS, sepsis and septic shock [2], and the predictive ability of NGAL in these patients is not so certain [3]. It is unclear, however, whether this predictive relationship is due to the fact that NGAL is produced by neutrophils and is, therefore, a biomarker of inflammation and infection, or whether NGAL in blood and/or urine mostly reflects tubular release. It is also unclear if the type of AKI that develops in SIRS is different from that developing in septic patients.