Randomised multiple centre trial of conservative versus liberal fluid administration for children receiving a kidney transplant (LIMITS): clinical trial protocol

Introduction In current practice, fluid volumes administered to children following kidney transplant vary widely. Up to 52% of children experience fluid overload-related complications. Current fluid guidelines are not evidence-based and the optimal amount of fluid for children after transplant is not known. The aim of Randomised multiple centre trial of conservative versus LIberal fluid adMInisTration for children receiving a kidney tranSplant (LIMITS) is to determine whether relative limitation of fluid volume administered to children receiving kidney transplants is superior to liberal fluid volume administration. Methods and analysis LIMITS is a pragmatic, open-label, UK-based, multicentre randomised controlled trial, with an internal pilot phase and integrated economic evaluation. A total of 140 children receiving kidney transplants will be randomised to receive either conservative postoperative fluid administration (maximum of 150 mL/m 2 /hour for no longer than 18 hours, followed by a fixed daily target of maximum 1.5 L/m 2 /day thereafter) versus the comparator of liberal postoperative fluid administration (fluid volume administered to replace urine output and insensible losses for at least 48 hours with target urine output >2 mL/kg/hour). The primary outcome is mean days at home in the first 30 days after kidney transplant. The primary outcome will be analysed using a mixed linear regression model adjusted for donor type (living vs deceased donor) and participant weight (<20 kg and ≥20 kg pretransplant) as fixed effects and transplant centre as a random effect. Cost-effectiveness will also be evaluated. Ethics and dissemination The trial received Health Research Authority approval on 20 August 2025 (REC reference: 25/EE/0161, IRAS project ID: 354370). Findings will be presented to academic groups via national and international conferences and peer-reviewed journals. The patient and public involvement group will play an important part in disseminating the study findings to the public domain. Trial registration number ISRCTN21516608 .