ORIGINAL ARTICLE Outcome of renal transplantation in small infants: a match-controlled analysis Marcus Weitz 1 & Guido F. Laube 1 & Maria Schmidt 1 & Kai Krupka 2 & Luisa Murer 3 & Dominik Müller 4 & Bernd Hoppe 5 & Anja Büscher 6 & Jens König 7 & Martin Pohl 8 & Therese Jungraithmayr 9 & Florian Thiel 10 & Heiko Billing 11 & Ryszard Grenda 12 & Jacek Rubik 12 & Michael M. Kaabak 13 & Fatos Yalcinkaya 14 & Rezan Topaloglu 15 & Nicholas Webb 16 & Luca Dello Strologo 17 & Lars Pape 18 & Silvio Nadalin 19 & Burkhard Tönshoff 2 Received: 10 October 2017 /Revised: 3 January 2018 /Accepted: 4 January 2018 # IPNA 2018 Abstract Background Infants with a body weight of less than 10 kg are often not considered to be suitable candidates for renal transplan- tation (RTx). The objective of this study was to evaluate this arbitrary weight threshold for pediatric RTx. Methods We conducted a multicenter, retrospective, match-controlled cohort study on infants weighing less than 10 kg at time of engrafting (low-weight group [LWG], n = 38) compared to a matched control group (n = 76) with a body weight of 10–15 kg, using data from the first 2 years post-transplant derived from the CERTAIN Registry. Results Patient survival was 97 and 100% in the LWG and control groups, respectively (P = 0.33), and death-censored graft survival was 100 and 95% in the LWG and control groups, respectively (P = 0.30). Estimated glomerular filtration rate at 2 years post-transplant was excellent and comparable between the groups (LWG 77.6 ± 34.9 mL/min/1.73 m 2 ; control 74.8 ± 29.1 mL/ min/1.73 m 2 ; P = 0.68). The overall incidences of surgery-related complications (LWG 11%, control 23%; P = 0.12) and medical outcome measures (LWG 23%, control 36%, P= 0.17) were not significantly different between the groups. The medical outcome measures included transplant-related viral diseases (LWG 10%, control 21%; P = 0.20), acute rejection episodes (LWG 14%, control 29%; P = 0.092), malignancies (LWG 3%, control 0%; P = 0.33) and arterial hypertension (LWG 73%, control 67%; P = 0.57). Conclusions These data suggest that RTx in low-weight children is a feasible option, at least in selected centers with appropriate surgical and medical expertise. Keywords Renal transplantation . Infants . Children . Surgical complications . Medical complications Introduction Pediatric renal transplantation (RTx) is the treatment of choice for children with end-stage renal disease (ESRD) [ 1]. Improved long-term patient survival, benefits in growth, phys- ical and cognitive development and a better quality of life favor early RTx [2]. Infants with a body weight of < 10 kg, however, represent a small patient population that is often not considered suitable for RTx [3]. Technical, physiologic, met- abolic and immunologic factors make small children uniquely different from older children and, consequently, appropriate timing of RTx in this patient population poses a major chal- lenge [3, 4]. The number of infants with ESRD is steadily increasing, and the frequently observed failure to thrive on chronic dialysis therapy leads to prolonged periods before transplantation associated with an increased risk of long- term morbidity and dialysis-related complications [ 5]. Therefore, pediatric nephrologists need to weigh competing priorities between the risks of early RTx for these children versus the disadvantages associated with prolonged dialysis therapy [6]. Current results on RTx in infants weighing < 10 kg are encouraging, but reports on the association of body weight at transplantation with post-transplant outcome may be Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00467-018-3895-5) contains supplementary material, which is available to authorized users. * Marcus Weitz marcus.weitz@kispi.uzh.ch Extended author information available on the last page of the article Pediatric Nephrology https://doi.org/10.1007/s00467-018-3895-5