Urinary neutrophil gelatinase-associated lipocalin after kidney transplantation: is it a good biomarker to assess delayed graft function?

Delayed graft function (DGF) is a common complication after transplantation. Its incidence is increased among patients receiving a graft from an expanded-criteria donor. Urinary neutrophil gelatinase-associated lipocalin (uNGAL), an acute kidney injury marker, could in the first days after transplantation be an early marker of DGF. We collected urine samples from 38 renal transplant recipients on days 1, 3, 6, and 10 post-transplantation, and months 1 and 6 creatinine to determine uNGAL, serum creatinine, Cystatin C, and albumin/creatinine ratio. We divided the patients into 2 groups, based on whether they developed DGF. We observed that mean uNGAL concentrations, Cystatin C, serum creatinine, and albumin/creatinine ratio were significantly lower in the non-DGF cohort on all measured days. uNGAL at day 3 showed a positive correlation with serum creatinine at day 10 (R = 0.58; P < .00) and day 30 (R = 0.57; P = .016) as well as with the length of hospital stay (r = 0.47; P < .00). Receiver operating characteristic analyses performed to assess the potential of uNGAL to predict DGF showed an area under the curve for day 3 of uNGAL of 0.917 (confidence interval [CI], 0.79-1.00; P = .00), with an optimal cutoff level of 124 ng/mL, sensitivity of 80% (CI, 62%-97%), and specificity of 83% (62%-104%; P = .001). In the first days after transplantation, uNGAL could be an early marker of DGF, providing additional information to standard biomarkers and potentially helping clinicians to take early measures to mitigate DGF.