Acute kidney injury (AKI) is a common complication of decompensated cirrhosis, and acute-on-chronic liver failure (ACLF) and is associated with a dismal mortality rate. [1] Clinicians must promptly and accurately identify the type of AKI in order to guide management, and in cases of hepatorenal syndrome (HRS-AKI), prescribe vasoconstrictors like telripressin to reverse the functional injury related to decreased circulating volume. [1] Distinguishing the structural kidney damage seen in acute tubular necrosis (ATN) from functional injury like prerenal AKI and HRS-AKI is a challenge in itself. Although there is no widely available diagnostic test that can do this on its own, the most recent set of guidelines from the International Ascites Club specifically calls for further study of urinary biomarkers of tubular injury to aid in the diagnosis of HRS-AKI. [1] In particular, urinary neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a leading candidate to fill this urgent clinical need. [2] In their retrospective cohort study, Gambino and Piano et al. assessed 90-day outcomes of 162 consecutive adult patients who were hospitalized with AKI and cirrhosis at a single center in Italy. [3] Their aim was to assess urinary NGAL's performance in (a) differentiating ATN from functional AKI in cirrhosis (i.e., prerenal AKI and HRS-AKI), (b) predicting shortterm mortality, and (c) predicting response to terlipressin treatment among those with HRS-AKI. Urinary NGAL was used as part of routine clinical care during the study period, and their population demographics were similar to those published in prior studies, [4,5] making this study an excellent snapshot of the "real clinical practice" performance of a test like NGAL. The authors demonstrated urinary NGAL's excellent ability to distinguish ATN (1162 ng/ml) from non-ATN AKI (87, 111, and 109 ng/ml for prerenal AKI, HRS-AKI and mixed AKI, respectively; p < 0.001). Using an optimal cutoff point of >220 ng/ml as the diagnostic threshold for ATN, the test performed well, with a sensitivity of 89% and specificity of 78% and an overall area under the curve (AUC) of 0.854. They also demonstrated that elevated NGAL was associated with 90-day mortality in adjusted and unadjusted Cox models. However, their most important finding was in their subgroup analysis of 64 terlipressin-treated patients with HRS-AKI.