title: The gut takes nearly all: threonine kinetics in infants.
abstract: BACKGROUND
  Threonine is an essential amino acid that is abundantly present in intestinally produced glycoproteins. Animal studies show that intestinal first-pass threonine metabolism is high, particularly during a restricted enteral protein intake.
  
  
  OBJECTIVE
  The objective of the study was to quantify intestinal first-pass threonine metabolism in preterm infants during full enteral feeding and during restricted enteral intake.
  
  
  METHODS
  Eight preterm infants (x +/- SD birth weight: 1.1 +/- 0.1 kg; gestational age: 29 +/- 2 wk) were studied during 2 periods. During period A, 40% of total intake was administered enterally and 60% was administered parenterally. Total threonine intake was 58 +/- 6 micromol kg(-1) h(-1). During period B, the infants received full enteral feeding, and the total threonine intake was 63 +/- 6 micromol kg(-1) h(-1). Dual stable-isotope tracer techniques were used to assess splanchnic and whole-body threonine kinetics.
  
  
  RESULTS
  The fractional first-pass threonine uptake by the intestine was remarkably high in both periods: 82 +/- 6% during partial enteral feeding and 70 +/- 6% during full enteral feeding. Net threonine retention was not affected by the route of feeding.
  
  
  CONCLUSIONS
  In preterm infants, the splanchnic tissues extract a very large amount of the dietary threonine intake, which indicates a high obligatory visceral need for threonine, presumably for the purposes of synthesis.
authors.affiliation: Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, Erasmus University, Rotterdam, Netherlands.
authors.forename: Sophie R D
authors.initials: SR
authors.lastname: van der Schoor
authors.forename: Darcos L
authors.initials: DL
authors.lastname: Wattimena
authors.forename: Jan
authors.initials: J
authors.lastname: Huijmans
authors.forename: Andras
authors.initials: A
authors.lastname: Vermes
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Goudoever
mesh_terms: D001682:Biological Availability; D002247:Carbon Isotopes; D004044:Dietary Proteins / Q000008:administration & dosage / Q000493:pharmacokinetics; D004750:Enteral Nutrition; D005260:Female; D006801:Humans; D007227:Infant Nutritional Physiological Phenomena; D007231:Infant, Newborn / Q000097:blood / Q000378:metabolism*; D007234:Infant, Premature / Q000097:blood / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D009587:Nitrogen Isotopes; D010084:Oxidation-Reduction; D010288:Parenteral Nutrition; D013912:Threonine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D014781:Viscera / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D004044:Dietary Proteins; D009587:Nitrogen Isotopes; D013912:Threonine