For example, Cystatin C concentrations are related to changes in glomerular filtration rate,22 whereas concentrations of NGAL are related to tubular stress or injury.23 Changes in these biomarkers with treatment or recovery suggest that they can also be used to monitor interventions.24 Furthermore, they can distinguish a majority of patients who do not have AKI according to creatinine-based criteria, but actually have a degree of kidney stres or injury that is associated with worse outcomes.25 Here, LCN2 is linked to acute kidney injury.