Background: Pediatric en-bloc kidney transplantation into adult recipients is an accepted technique to expand the donor pool. Concerns about adequate "nephron dosing" have traditionally favored placing these kidneys into smaller recipients.
Methods: We reviewed 20 pediatric en-bloc transplants performed at our institution between 2002 and 2008. We examined the impact of donor age, donor weight, recipient sex, combined kidney length, recipient weight, recipient-to-donor weight ratio, and recipient weight gain on serum creatinine over time using regression analysis.
Results: Patient survival was 100%. Two grafts were lost early from vascular thrombosis. Of the remaining 18 recipients, all had immediate and excellent long-term function with average creatinine of 0.91+/-0.38 mg/dL at a mean follow-up of 1257+/-656 days. For 17 patients with 1 year follow-up, recipient weight, recipient-to-donor weight ratio, and recipient male sex negatively influenced renal function at 1 month. However, this relationship was lost by 1 year with increasing function in the smallest donors and largest size mismatches. Between 1 month and 1 year posttransplant, estimated creatinine clearance improved from 59+/-13 mL/min at 1 month posttransplant to 88+/-41 mL/min (P<0.015). Weight gain after transplant was associated with improved creatinine clearance, suggesting continued adaptation over time.
Conclusions: We conclude that donor or recipient size matching up to a recipient-to-donor weight ratio of 7.5 does not significantly impact later renal function after pediatric en-bloc kidney transplantation into adults.