Urinary neutrophil gelatinase-associated lipocalin (NGAL) as early marker of delayed graft function in kidney transplanted patients

BACKGROUND. Kidney transplantation is frequently complicated by delayed graft function (DGF). DGF means the necessity of resorting to the dialysis treatment within a week after kidney transplantation. DGF may be dependent on the donor, the recipient, and the graft itself. DGF is associated with more frequent episodes of acute rejection, increased need of post-transplantation biopsies, dialysis sessions and prolonged hospitalization. These complications not only increase the costs of transplantation but they also have negative impact on long-term survival. Urinary NGAL, is regarded as acute kidney injury marker. This preliminary study aimed at evaluating whether NGAL may be used as early predictor of DGF in kidney transplanted patients. METHODS. Urinary analysis of NGAL (Architect, Abbott), creatinine (Modular, Roche), NGAL/creatinine ratio, and daily NGAL excretion were performed in the samples from 14 renal transplant recipients on post-transplantation days 1, 2, 3, 4, 5. RESULTS. DGF was observed in 3 patients (21,2 %). Urinary NGAL concentrations (ng/mL) were broadly variable. Using the analysis of variance (ANOVA), the patients who did not experience DGF (n=11) showed that only NGAL/creatinine ratio (ng/mg of creat) and NGAL excretion (mg/day) were significantly lower (p < 0.05) on day 2, 3, 4, and 5 compared to day 1. Moreover, patients who experienced DGF the levels of NGAL excreted were significantly lower (p < 0.05) during the first observational day compared to non-DGF-patients. It is worth mentioning that the levels of NGAL excreted in patients who experienced DGF were low during the first two days, afterward, at the 5th day NGAL levels were statistically increased (p = 0.016) compared to non-DGF-patients. CONCLUSIONS. The data of the present study provide additional information on clinical use of urinary NGAL measurements. The values of NGAL/creatinine ratio and NGAL excretion measured during the first days following kidney transplantation could be considered as early predictors of DGF. Although the sample size of this study does not permit to draw strong conclusions, the data attained may be hypothesis generating for larger controlled studies