Serum Neutrophil Gelatinase-Associated Lipocalin and Cystatin C for Assessing Recovery of Graft Function in Patients Undergoing Living-Donor Kidney Transplantation.

Background: Neutrophil gelatinase-associated lipocalin (NGAL) can be used as an early indicator of acute kidney injury (AKI), and cystatin C is also suggested to be an ideal marker of glomerular filtration rate (GFR), but they were not sufficiently studied in recipients without delayed graft function (DGF) after living-donor kidney transplant (LDKT). The aim of the study is to investigate whether serum NGAL and cystatin C can assess the recovery of renal function after LDKT.

Methods: 49 adult patients that had undergone LDKT between January 2012 and March 2014 were prospectively enrolled. Serum creatinine, NGAL, and cystatin C were measured on day 0-7, day 10, day 14 and month 9 after transplant. Recovery of graft function was evaluated by the time needed to reach eGFR > or = 60 mL/min/1.73 in2 Poor long-term graft outcome was defined as eGFR < 60 mL/min/1.73 M2 at 9 months.

Results: No DGF was recorded. Serum NGAL level decreased to normal earlier than creatinine after transplant. Cystatin C declined rapidly, but still stayed above the normal range. Serum NGAL on day 0 (p = 0.028) and cystatin C on day 2 (p < 0.001) were independent predictors of the time for graft function recovery in multivariate analysis. Compared to recipients with fair long-term graft outcome (eGFR > 60 mL/min/1.73 m2 at 9 months), recipients with poor long-term graft outcome (eGFR < 60 mL/min/1.73 m2 at 9 months) displayed higher serum NGAL on day 2 (p = 0.045), older age (p = 0.002), longer time on dialysis (p = 0.02), and lower donor eGFR (p = 0.045). There were correlations between serum NGAL and eGFR on day 0 and day 2. Correlations between serum cystatin C and eGFR on day 0, day 2, and month 9 were all significant.

Conclusions: Serum NGAL may be used as an early predictor of recovery of post-transplant graft function after LDKT, but may not be used for real-time assessment of GFR. At the same time, the predictive ability of serum cystatin C needs to be further assessed.