Urinary NGAL has been shown to be an early marker of acute kidney injury (AKI) following paediatric cardiac surgery (2 hours off pump). Previous studies showed that an early increase of urinary NGAL following cardiopulmonary bypass was predictive of AKI. Several studies included heterogeneous populations of children undergoing cardiac surgery, but NGAL has not been studied in neonates after open heart surgery, neither has been identified the threshold for accurate prediction of severe AKI requiring renal replacement therapy.