Better long-term functional adaptation to the child's size with pediatric compared to adult kidney donors

Background. Pros and cons for pediatric kidney donors have been debated, especially with respect to survival rates. However, the effect of donor age on kidney function remains conflicting. The aim of this study was to compare short and long-term renal function according to the age of the donor, in grafts from adult living related (LRD), adult cadaveric and pediatric cadaveric donors (PedCD) following pediatric transplantation (Tx). Methods. One hundred and thirty-four children were repeatedly followed for four years, and 44 were followed for eight years. Absolute and relative glomerular filtration rate (GFR; inulin clearance, mL/min and mL/min/1.73 m(2) , respectively) were determined within 6 months, and yearly thereafter. Results. Absolute GFR increased along with body growth in the PedCD group (P < 0.001) during the 4 years following Tx, leading to stable relative GFR, whereas absolute GFR of the LRD group did not change, with a progressive decrease of relative GFR (P < 0.001). Relative GFR did not differ between PedCD and LRD recipients by the sixth month but became higher in PedCD 4 years post-Tx (70 +/- 25 vs 52 +/- 19 mL/min/1.73 m(2) , P < 0.001). Among those followed for 8 years, relative GFR showed a slow decrease in both recipient groups from 6 years post-Tx. At 8 years post-Tx, relative GFR was still significantly higher in PedCD than in LRD (57 +/- 19 vs. 45 +/- 19; P < 0.05). Conclusions. Adult-sized grafts may adapt to pediatric recipients during the first months post-Tx, but graft function cannot improve thereafter along with the increase in body size of the recipient. Interestingly, the absolute GFR of children receiving pediatric grafts increased along with body growth, leading to a stable relative GFR up to 6 years post-Tx.