Introduction: Renal mass plays an important role for a balanced graft function after transplantation. Our aim is to evaluate the relation between transplanted renal mass and long term graft outcomes in pediatric renal transplant recipients.
Materials and Methods: Forty six children (M/F: 26/20) with kidney transplant from living related donor were enrolled to the study. Demographic data and laboratory findings were noted. The estimated glomerular filtration rate (eGFR) was calculated by Schwartz Formula. Grafts (Gw) and recipients (Rw) were weighed before transplantation. Patients were divided into three groups according to the Gw/Rw ratios (Gw/Rw<3.9 (P25), Gw/Rw=3.9-9.3 (P25-P75), Gw/Rw>9.3 (P75)). Relation between Gw/Rw ration and allograft outcomes was evaluated.
Results: Mean age at the time of the transplantation was 14.09±4.71 years. Mean age of donors (M/F:20/26) was 37.97±0.94 years. Mean follow-up time after transplantation was 3.87±1.08 years. Mean weight of recipients was 35.04±2.57 kg, mean weight of donors was 77.06±1.72 kg.  Mean Gw/Rw ratio was 6.63±3.69. Delayed graft function was not observed. At 3rd years of follow-up, mean creatinine level was 0.89±0.26 mg/dl and mean GFR value was 97.07±16.86 ml/min. A statistically significant negative correlation was demonstrated between Gw/Rw ratio and creatinine levels at 3rd and 6th months and 1st and 3rd years of follow-up (r=-7.00, p<0.01, r=-7.28 p<0.01, r=-4.70 p<0.01, r=-5.86 p<0.05). Patients with Gw/Rw>9.3 had lowest mean creatinine levels during the first 6 months of transplantation when compared with patients with Gw/Rw ratio<3.9; but this difference between creatinine levels could not be demonstrated after 6th month of transplantation. Gw/Rw ratio was not associated with acute rejection episode and HLA mismatch. Gw/Rw ratio was not an independent risk factor for graft survival at 3rd year of follow-up in a multivariate logistic regression analysis.
Conclusion: We demonstrated a significant relation between renal mass and creatinine levels after transplantation. Pediatric renal transplantation from an adult donor is mostly results with higher Gw/Rw ratio. Higher Gw/Rw ratio can cause hyperfiltration during the first 6 months of transplantation, but it has no effect on long term outcomes.