Effect of Donor-recipient Size on Graft Growth in Pediatric Donor-to-pediatric Recipient Kidney Transplantation

Kidney transplantation is the optimal treatment for pediatric end-stage kidney disease, yet donor shortages have driven the use of pediatric donor kidneys through pediatric donor-to-pediatric recipient (PTP) kidney transplantation. This study aimed to investigate the effect of donor-recipient size on graft growth in PTP kidney transplantation.

This retrospective cohort study included kidney transplant recipients who underwent regular follow-ups between January 2016 and December 2023 at the Children's Hospital of Fudan University. All donors were deceased and aged <18 y. Dynamic clinical data were obtained from medical records spanning the pretransplant to posttransplant period.

A total of 136 patients were enrolled, 93 of whom had an initial transplant kidney length. Cumulative average growth of kidney length was 5.5 mm at 1 mo, 9.9 mm at 3 mo, 15.3 mm at 6 mo, 22.3 mm at 1 y, 31.5 mm at 3 y, and 39.5 mm at 5 y posttransplant. The corresponding growth rates were 8.3%, 15.1%, 22.3%, 30.6%, 41.3%, and 53.4%. Kidney growth rates were negatively correlated with the donor-recipient body weight ratio at 3 mo, 6 mo, and 1 y posttransplant (P < 0.01). The mean estimated glomerular filtration rate at the last follow-up was 84.1 ± 31.8 mL/min/1.73 m². Posttransplant estimated glomerular filtration rate showed a significant positive correlation with donor-recipient body weight ratio during the early posttransplant period (1, 3, and 6 mo; P < 0.01). Smaller grafts required approximately 6 mo to reach a normative size consistent with the recipients' age.

Grafts showed stable growth patterns and favorable short-term follow-up outcomes. Additionally, PTP kidney transplantation demonstrated both clinical value and practical utility.