Kidney Transplantation in Children Weighing Less than 15 kg: A 35-Year Single-Center Experience

Background: Kidney transplantation is the treatment of choice for pediatric patients with end-stage kidney disease. However, transplantation in children weighing < 15 kg remains challenging due to limited donor availability and higher surgical and medical risks. We report our 35-year single-center experience in this population, focusing on perioperative and long-term outcomes. Methods: We retrospectively analyzed kidney transplants performed from 1987 to 2023 in children weighing < 15 kg. Data on demographics, donor type, complications, immunosuppression, and outcomes at 2, 5, and 10 years (including survival, graft function, rejection, infections, and urological issues) were collected. Outcomes were compared between deceased and living donors and between recipients weighing < 10 kg and ≥10 kg. Results: Ninety-six transplants were included (mean age 3.3 years; mean weight 11.1 kg), 80 from deceased and 16 from living donors. Most patients (69.8%) had been treated with peritoneal dialysis. Median follow-up was 120 months. Patient survival was 95.8%; graft survival was 78.1%. Eight grafts (8.3%) were lost to renal vein thrombosis, all in deceased-donor recipients (p = 0.60). Preserved renal function (eGFR > 60 mL/min/1.73 m²) declined from 80.4% at 2 years to 66.0% at 5 years and 18.0% at 10 years. Graft survival at 10 years was significantly lower in children < 10 kg vs. ≥10 kg (49.6% vs. 80.3%, p = 0.003). CAKUT was associated with higher urological complication rates (p = 0.017). No significant differences emerged between living and deceased donor groups. Conclusions: Transplantation in children < 15 kg is feasible with good outcomes, but those <10 kg present lower graft survival at 10 years. Multidisciplinary assessment and center experience are key to optimizing results.