The Effect of Branched-chain Amino Acids on Blood Urea Nitrogen Levels in Intensive Care Unit and Patients Receiving Total Parenteral Nutrition: A Narrative Literature Review

This review was conducted as a narrative literature review using a structured approach to identify, select, evaluate, and synthesize studies on the relationship between branched-chain amino acid (BCAA) supplementation and blood urea nitrogen (BUN) levels in intensive care unit (ICU) and total parenteral nutrition (TPN) patients, guided by Preferred Reporting Items for Systematic reviews and Meta-Analyses and Cochrane recommendations where applicable. Among the key evidence, the PEPaNIC randomized controlled trial investigated early versus late initiation of parenteral nutrition in critically ill children up to 17 years of age admitted to pediatric ICUs in Belgium, Canada, and the Netherlands. In a prespecified subanalysis focusing on term neonates (≤28 days old), outcomes were assessed across overlapping age groups with enteral nutrition initiated as soon as feasible. Outcome assessors were blinded, and analyses were intention-to-treat with adjustments for severity and demographic factors. The study demonstrated that the timing of nutrition initiation influenced the incidence of new infections and ICU dependency, while secondary safety outcomes included mortality and hypoglycemia. These findings highlight how nutritional strategies, including amino acid supplementation, can impact metabolic markers such as BUN and clinical outcomes, providing a relevant foundation for evaluating the potential role of BCAA supplementation in critically ill patients.