CST3 and acute kidney injury: For example, a recent study suggested that GFR may be significantly overestimated using creatinine compared with cystatin C in critically ill patients, resulting in inflated estimates of kidney function and recovery after AKI.9 In addition, despite tubular damage being the primary concern in AKI, only a few studies have begun to examine specific aspects of tubular health during and after AKI,10 the latter of which may provide insights to better link AKI to other long-term outcomes and help guide certain aspects of management.