Plasma neutrophil gelatinase-associated lipocalin (NGAL) for timing of initiation of renal replacement therapy for acute kidney injury?

Renal replacement therapy (RRT) for acute kidney injury (AKI) has been in use in critically ill patient since the first successful treatments done by William Kolff during the mid-1940-ties (1). Similar to many other invasive treatments used in the intensive care unit (ICU) such as mechanical ventilation, decompressive craniotomy, or intra-aortic balloon pump and despite over 6 decades of experience, the optimal timing of initiation of RRT for AKI is still a matter of debate (2).