Renal function changes over time in adult recipients of small pediatric kidneys - Evidence against hyperperfusion injury

There has been considerable debate regarding the use of pediatric donor kidneys in adults with endstage renal disease. These small kidneys may not be able to deal with the metabolic demands of the large adult size, and thus pediatric kidneys may be at higher risk of loss due to hyperperfusion injury. To study the impact of small kidney size on renal outcome, we studied two groups of patients. This retrospective review of patients at a single institution compared recipients of pediatric renal transplants (age <7 years, n=37) to a matched group of adult-kidney recipients (1:2 ratio, n=74). The groups were matched for age, sex, diabetic status, HLA type, and duration of follow-up. Primary outcomes of interest were: calculated creatinine clearance at 6 months, 1 year, 2 years, and 3 years after transplantation and evidence of hyperperfusion damage as determined by proteinuria, graft biopsy, and late graft loss due to chronic rejection. This study demonstrates no significant difference in calculated creatinine clearance between pediatric and adult transplants at 6 months (43.8 vs. 50.7 ml/min, respectively) or at 3 years after transplantation (56.3 vs. 56.2 ml/min), nor was there any evidence of increased proteinuria or late graft loss in the pediatric-kidney recipients compared with adult-kidney recipients. Our data do not demonstrate the detrimental effects of small kidney size relative to recipient on subsequent renal outcomes, and thus support the practice of pediatric donor kidneys being used in adult recipients when pediatric recipients are not available.