Are we ready for the clinical use of novel acute kidney injury biomarkers?

Acute kidney injury (AKI) is a common event in several neonatal populations, and those neonates with AKI have poor outcomes. Serum creatinine (SCr)-based definitions of AKI are not ideal and are additionally limited in neonates whose SCr reflects the maternal creatinine level at birth and normally drops over the first weeks of life dependent on gestational age. Recent studies show that urine and serum biomarkers may provide a better basis than SCr on which to diagnose AKI. In this month's issue of Pediatric Nephrology, Sarafidis et al. show that urine neutrophil gelatinase-associated lipocalin (uNGAL), serum NGAL (sNGAL), and urine cystatin c (uCysC) are highest in those neonates with asphyxia who have elevated SCr. Furthermore, those with asphyxia without a concomitant rise in SCr levels have elevated levels of biomarkers compared to controls, suggesting a dose response. Once the SCr level returns to normal, the levels of novel AKI biomarkers continue to be elevated. While these findings strengthen the argument for the clinical use of these AKI biomarkers, further work is needed before they can be implemented in clinical practice. Large-scale observational multi-center studies are needed to test these biomarkers against hard clinical endpoints. In addition, randomized intervention trials which use biomarkers to define AKI need to be performed.