NGAL and AKI: the end of a myth?

Excerpt

Neutrophil gelatinase–associated lipocalin (NGAL), also called lipocalin-2, is a 25 kD protein of the lipocalin superfamily expressed and secreted by numerous cells including immune cells, hepatocytes and renal tubular cells [1]. Beyond its bacteriostatic activity, numerous observations have suggested that NGAL might act as a growth and differentiation factor in several cell types, including renal epithelia [2]. Report of a massive up-regulation of NGAL expression following renal tubular injury created interest in this molecule as a promising candidate to detect renal injury earlier and more reliably than conventional markers of renal function [3]. Hence, first investigations suggested urinary NGAL to be both highly sensitive and specific in predicting acute kidney injury (AKI) [4, 5]. Although some studies confirmed the excellent performance of urinary or plasma NGAL as a biomarker of AKI or renal replacement therapy (RRT) in larger unselected cohorts of critically ill patients [6, 7], substantial variation was observed across studies [8]. Additionally, several conditions were identified which may interfere with NGAL performance such as sepsis [9], COPD [10] or cardiac dysfunction [11] and act as confounding factors. Finally, the performance of NGAL appears to be influenced by age (superior prediction in children) [12], by sex and baseline renal function [13]. …