The elusive task of biomarkers of renal injury.

Neutrophil gelatinase-associated lipocalin (NGAL) is one of the most promising candidate biomarkers of renal injury, with expression in renal tissue increasing dramatically after ischemia-reperfusion injury but not in the case of pure pre-renal failure. In a recent issue of Critical Care, Di Somma and colleagues reported that NGAL could improve the classification of acute kidney injury compared with clinical assessment and showed that NGAL was associated with poor prognosis. NGAL may therefore carry different information than biomarkers of renal function. This study finally provides additional evidence for the highly complex relationship between renal function and renal injury.