Efficacy of Teduglutide in Pediatric Short Bowel Syndrome: Association with Citrulline Levels and Anatomical Location of Remnant Small Intestine

<b>Background/Objectives:</b> Short bowel syndrome (SBS) is the leading cause of pediatric intestinal failure. Plasma citrulline is considered a marker indicating an enterocyte volume and may help evaluate the response to teduglutide; however, this interpretation may vary depending on the remnant bowel anatomy. <b>Methods:</b> We conducted a retrospective case series of four pediatric patients with SBS (aged < 15 years) who received teduglutide for 12 months at our hospital between 2018 and 2023. Changes in plasma citrulline levels and parenteral nutrition requirements were assessed in addition to bowel anatomy classification. <b>Results:</b> This study included two males and two females. All patients showed an increase in plasma citrulline levels and a reduction in the requirement for parenteral nutrition (PN) after 12 months of teduglutide treatment. In SBS type 2 (jejunocolic anastomosis), citrulline levels increased by 114% and 52%, with PN reduction rates of 100% and 30%, respectively. In SBS type 3 (jejunoileal anastomosis), citrulline levels increased by 13.6% and 34%, with PN reductions of 33% and 73%, respectively. <b>Conclusions:</b> Teduglutide treatment increased plasma citrulline levels and reduced PN levels in all cases. However, the magnitude of the citrulline change varied across bowel anatomy types, suggesting that the anatomical difference in the remnant bowel may influence the biomarker response. Further detailed pediatric cases are required to clarify the role of citrulline in evaluating GLP-2 analogue treatment outcomes.