title: Lysine requirement in parenterally fed postsurgical human neonates.
abstract: BACKGROUND
  The lysine requirement of human neonates receiving parenteral nutrition (PN) has not been determined experimentally.
  
  
  OBJECTIVE
  The objective was to determine the parenteral lysine requirement for human neonates by using the minimally invasive indicator amino acid oxidation technique with l-[1-(13)C] phenylalanine as the indicator amino acid.
  
  
  METHODS
  Eleven postsurgical neonates were randomly assigned to 15 lysine intakes ranging from 50 to 260 mg . kg(-1) . d(-1). Breath and urine samples were collected at baseline and at plateau for (13)CO(2) (F(13)CO(2)) and amino acid enrichment, respectively. The mean lysine requirement was determined by applying a 2-phase linear regression crossover analysis to the measured rates of F(13)CO(2) release and l-[1-(13)C]phenylalanine oxidation.
  
  
  RESULTS
  The mean parenteral lysine requirement determined by F(13)CO(2) release oxidation was 104.9 mg . kg(-1) . d(-1) (upper and lower CIs: 120.6 and 89.1 mg . kg(-1) . d(-1), respectively). The mean lysine parenteral requirement determined by phenylalanine oxidation was 117.6 mg . kg(-1) . d(-1) (upper and lower CIs: 157.5 and 77.6 mg . kg(-1) . d(-1), respectively). Graded intakes of lysine had no effect on phenylalanine flux.
  
  
  CONCLUSIONS
  We recommend a mean lysine requirement for the postsurgical PN-fed neonate of 104.9 mg . kg(-1) . d(-1), which is 32-43% of the lysine concentration presently found in commercial PN solutions (246-330 mg . kg(-1) . d(-1)). This trial was registered at clinicaltrials.gov as NCT00779753.
authors.affiliation: Research Institute, The Hospital for Sick Children, Toronto, Canada.
authors.forename: Karen P
authors.initials: KP
authors.lastname: Chapman
authors.forename: Glenda
authors.initials: G
authors.lastname: Courtney-Martin
authors.forename: Aideen M
authors.initials: AM
authors.lastname: Moore
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Langer
authors.forename: Christopher
authors.initials: C
authors.lastname: Tomlinson
authors.forename: Ronald O
authors.initials: RO
authors.lastname: Ball
authors.forename: Paul B
authors.initials: PB
authors.lastname: Pencharz
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D041981:Gastrointestinal Tract / Q000601:surgery; D006801:Humans; D007231:Infant, Newborn; D007553:Isotope Labeling; D008239:Lysine / Q000008:administration & dosage* / Q000652:urine; D008297:Male; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D010288:Parenteral Nutrition; D010649:Phenylalanine / Q000378:metabolism; D011184:Postoperative Period
chemical_list: D002245:Carbon Dioxide; D010649:Phenylalanine; D008239:Lysine