Protocol biopsies in pediatric renal transplantation: a precious tool for clinical management

Kidney transplantation is the best treatment for children with end-stage kidney disease. Early results have improved, but late graft loss is still a major problem. Non-invasive, fully reliable early biomarkers of acute rejection are currently missing.

Our aim was to evaluate the efficacy of protocol biopsies (PBXs) in a pediatric population. During 11 years, 209 renal transplantations were performed in 204 pediatric patients. Biopsies were performed 3-6 months, 1 year, and 5 years after transplantation. Procedure-related complications were systematically looked for by means of ultrasound scans.

Unexpected findings (mainly subclinical rejections) requiring therapeutic intervention were found in 19.3% biopsies performed at 3-6 months, in 18.4% in 12-month biopsies and in none of those performed after 5 years. The 13.6% patients at 12-month biopsies and 23.6% at 5-year biopsies showed calcineurin inhibitor (CNI) toxicity. Interstitial fibrosis and tubular atrophy (IF/TA) was found in 17.6 and 83.6% of patients at 12-month and 5-year biopsies, respectively. Complications of the PBX were infrequent. Five-year estimated glomerular filtration rate (GFR) was not significantly different in patients who received treatment for any cause and patients with normal histology.

Although we do not have a control group, we may speculate that patients who received treatment returned to a "standard" condition possibly improving final outcome. Protocol biopsies are a powerful diagnostic tool for the management of pediatric renal transplant recipients. In view of the lack of evidence that biopsies taken 5 years after transplantation lead to any therapeutic change, their use should be reconsidered.