However, this interpretation is challenged by the work of Husain-Syed and colleagues who have demonstrated that increased urinary TIMP-2•IGFBP7 after cardiac surgery is associated with loss of renal functional reserve at three months even in the absence of AKI.14 It may be that crude measures, such as death or dialysis, do not change when kidney stress occurs without dysfunction, but measuring renal functional reserve may reveal that this stress resulted in kidney damage. Here, IGFBP7 is linked to acute kidney injury.