Urinary neutrophil gelatinase-associated lipocalin is a biomarker of delayed graft function after kidney transplantation

Background: Acute kidney injury occurring after kidney transplantation frequently leads to delayed graft function with detrimental long-term effects on graft survival. Neutrophil gelatinase-associated lipocalin (NGAL) has been validated as a biomarker for posttransplant acute kidney injury. This observational study aimed to assess the effectiveness of urinary NGAL as a predictive marker of delayed graft function. Materials and methods: Forty-three consecutive patients who received renal transplant were included in the study. Urine samples were collected before transplant (if available) and at days 1, 3, 7, 14, and 30 after transplant, and urinary NGAL levels were quantified by enzyme-linked immunosorbent assay. Results: Urinary NGAL progressively decreased after transplant in patients with both delayed and immediate graft function. However, urinary NGAL concentration remained significantly higher in the presence of delayed graft function in the first 14 days after transplant. The area under the receiver operating characteristic curve showed that the ability of urinary NGAL to predict delayed graft function was accurate at 1st and 3rd days after transplant. Conclusion: The relative decrease of urinary NGAL concentration rather than its absolute value may be relevant to predict delayed graft function after renal transplant. In particular, urinary NGAL area under the curve for 3 days seems to be a more valuable parameter of decision making in the early posttransplant period.