Donor-Recipient Size Matching Influences Early But Not Late Graft Function After Pediatric En-Bloc Kidney Transplantation

Abstract

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. 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. 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. 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.