LCN2 and acute kidney injury: Although the AUCs in our study were not as robust as in previous studies, as noted above, our study differed in the following ways: AKI timing in our patients was unknown (unlike the CPB and immediate post-renal transplant patient populations, where NGAL concentrations can be tested at different specific time points after the event that incites AKI); and our population was heterogeneous as compared with uNGAL studies in primary renal disease.