Determining whether an elevation in serum creatinine represents structural damage or a reversible functional change is a dilemma that clinicians encounter frequently. The emergence of kidney-specific biomarkers offers an opportunity to improve our discriminatory ability. Singer et al. provide new information on the utility of neutrophil gelatinase-associated lipocalin (NGAL) to distinguish pre-renal from established acute kidney injury. Although these results are promising, several caveats need to be considered and applied for future confirmatory studies.
