Are serum and urine neutrophil gelatinase-associated lipocalin predictive of renal graft function in short term?

NGAL is a member of the lipocalin protein family that has diverse function but similar structure. The functions of NGAL are not clear, but it appears to be expressed in stress conditions and in tissues undergoing involution. Varied studies have shown increased levels of plasma or urinary NGAL in diverse renal damages. The aim of this study was the serial measurement of serum and urinary NGAL within the first week after renal transplantation in children to predict immediate and short-term graft function. A total of 27 patients were assessed. These patients were classified into those with rapid reduction in serum creatinine (more than 50% reduction in serum creatinine in the first day after transplantation) and patients with slow reduction in serum creatinine (<50% reduction in serum creatinine). We also assessed the absolute reduction in serum creatinine before and after transplantation. Serum and urinary NGAL on the first day post-transplantation were higher in recipients with slow reduction in serum creatinine (urinary NGAL at the first day: 197 ± 153 [s.e.m.] vs. 22.54 ± 8.5 [s.e.m.], p = 0.04; serum NGAL at the first day: 199 vs. 69.8, p = 0.003). The cutoff point of serum NGAL at the first day after transplantation for prediction of slow creatinine reduction was 174 ng/mL with a sensitivity of 100% and specificity of 95.5%. However, we did not find association between the absolute reduction in serum creatinine before and after transplantation with the amount of serum and urinary NGAL post-transplant. Additionally, we did not find any effect of high serum and urine NGAL concentration on the graft function at the first year post-transplant. Although it is supposed that high serum and urine NGAL may predict ischemia of graft in early phases; however, it appears that this mild ischemic injury to graft without DGF or SGF cannot affect the graft function in short-term period. Further studies are needed using larger transplant recipients in pediatric age group. It is also needed to determine the effects of mild ischemic injuries on the graft function in long-term period in future studies.