Urinary Neutrophil Gelatinase-Associated Lipocalin Does Not Distinguish Acute Rejection from Other Causes of Acute Kidney Injury in Pediatric Renal Transplant Recipients

Background: The aim of this prospective single center study was to investigate the ability of urinary neutrophil gelatinase-associated lipocalin (NGAL) to distinguish acute rejection from other causes of acute kidney injury (AM) in children after renal transplantation. Methods: Fifteen children fulfilled the inclusion criteria (acute kidney injury (AKI) with allograft biopsy, at least 21 days after renal transplantation, no sepsis) during 2013 - 2014 in our pediatric transplantation center. The mean age was 14.8 +/- 2.8, median time after renal transplantation was 0.4 years (range 0.1 - 3.8). Urinary NGAL was measured in spot urine by Chemiluminescent Microparticle Immunoassay technology. Results: Four patients had biopsy proven acute rejection (rejection group), eleven children had AM of other cause (non-rejection group). The median urinary NGAL concentration in the rejection group was not significantly different from NGAL in the non-rejection group (7.3 ng/mL, range 3.0 - 42.3 vs. 8.6 ng/mL, range 3.4 - 54.7, p = 0.48). There was a significant negative correlation between eGFR and urinary NGAL concentrations (r = -0.77, p < 0.001). Conclusions: Our small study suggests that in children after renal transplantation, urinary NGAL cannot be used as a specific marker for distinguishing acute rejection from other non-rejection causes of AM. Urinary NGAL was mainly associated with graft function but not with the etiology of AKI.