How Young is Too Young for Pediatric-to-Adult Kidney Transplants?

We all know that there is a drastic shortage of donor kidneys available: in the state of Massachusetts, for instance, the average time on the kidney transplant waiting list we're quoting to patients is about 5 years...which for many elderly patients just starting dialysis exceeds their anticipated life expectancy!

One potential strategy to increase the number of donor kidneys available is to accept kidneys from either the very old or the very young. With regards to the latter, pediatric kidneys--transplanted either into children, or into adults--have been used for many decades. However, the preferred method of transplantation has been to transplant BOTH kidneys from the pediatric donor en bloc to an adult recipient, in order to provide sufficient nephron mass to allow adequate renal function in an adult.

A recent CJASN article by Zhang et al asks the question whether or not it is possible to divide up kidneys from a single pediatric donor into different recipients in order to effectively double the usefulness of available pediatric donor kidneys. The transplant program at Tulane University performed an analysis of two groups of adult patients: those who received pediatric kidneys from donors less than 5 years of age ("Group 1"), and those who received pediatric kidneys from donors between 5 and 10 years of age ("Group 2"). Interestingly, despite a higher rate of rejection in Group 1 compared to Group 2, the overall graft function outcomes were similar in both groups at 5 years. The authors conclude that single pediatric kidney transplants from donors younger than 5 years of age can be used with acceptable complications and long-term outcomes. The youngest donor in this study was a 9-month old girl weighing only 8 kg, with a kidney length of only 5cm, and strikingly both kidneys still functioning well 5 years out in different recipients!