Is urinary γ-glutamyl transpeptidase superior to urinary neutrophil gelatinase-associated lipocalin for early prediction of acute kidney injury after liver transplantation?
In this prospective study, we comparatively evaluated the accuracy of several biomarkers of acute kidney injury (AKI) on predicting its occurrence after liver transplantation (LT). The parameters evaluated were urinary tubular enzymes (γ-glutamyl transpeptidase [γGT], alkaline phosphatase, and urinary lactate dehydrogenase) and urinary neutrophil gelatinase-associated lipocalin. These parameters were evaluated both as isolated variables and divided by urinary creatinine. Samples were collected by the end of surgery (determination 1) and at 12 to 24 hours after surgery (determination 2). The study endpoint was the development of AKI. The study was performed over a 1-year period, and 61 of 77 patients were enrolled (main exclusion criteria were perioperative death, previous known renal failure, and insufficient data for analysis). Of these 61 patients, AKI was observed in 19 (group 1). The main relevant parameter to predict AKI was the absolute value of urinary γGT at determination 1 (area under the curve, 0.74; specificity, 72.5%; sensitivity, 70.3%; cutoff, 36 U/mL). Urinary neutrophil gelatinase-associated lipocalin was not as accurate; the best predicted value for this parameter was absolute value at D1 with an area under the curve of 0.5 (specificity, 84.2%; sensitivity, 35.7%; cutoff value, 44.6 ng/mL). We concluded that the absolute value of urinary γGT evaluated at the end of LT was the most accurate parameter to predict AKI in our cohort. Urinary enzyme levels must be taken into account in future analysis of this issue.