Total sulfur amino acid requirement and metabolism in parenterally fed postsurgical human neonates.
BACKGROUND
Except for tyrosine, the amino acid requirements of human neonates receiving parenteral nutrition (PN) have not been experimentally derived.


OBJECTIVE
The objectives were to determine the total sulfur amino acid (TSAA) requirement (methionine in the absence of cysteine) of postsurgical, PN-fed human neonates by using the indicator amino acid oxidation (IAAO) technique with L-[1-(13)C]phenylalanine as the indicator.


METHODS
Fifteen postsurgical neonates were randomly assigned to receive 1 of 18 methionine intakes ranging from 10 to 120 mg x kg(-1) x d(-1), delivered in a customized, cysteine-free amino acid solution. Breath and urine samples were collected for the measurement of (13)CO(2) and amino acid enrichment. Blood samples were collected at baseline and after the test methionine infusion for the measurement of plasma methionine, homocysteine, cystathionine, and cysteine concentrations.


RESULTS
Breakpoint analysis determined the mean TSAA requirements to be 47.4 (95% CI: 38.7, 56.1) and 49.0 (95% CI: 39.9, 58.0) mg x kg(-1) x d(-1) with the use of oxidation and F(13)CO(2), respectively.


CONCLUSIONS
This is the first study to report the TSAA requirement of postsurgical, PN-fed human neonates. The estimated methionine requirement expressed as a proportion of the methionine content of current commercial pediatric PN solutions was 90% (range: 48-90%) of that found in the lowest methionine-containing PN solution.
Courtney-Martin
Glenda
G
Research Institute, The Hospital for Sick Children, Toronto, Canada.
Chapman
Karen P
KP
Moore
Aideen M
AM
Kim
Jae H
JH
Ball
Ronald O
RO
Pencharz
Paul B
PB
D000603:Amino Acids, Sulfur / Q000008:administration & dosage* / Q000378:metabolism*; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D003545:Cysteine / Q000008:administration & dosage / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007227:Infant Nutritional Physiological Phenomena / Q000502:physiology*; D007231:Infant, Newborn; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000378:metabolism; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D010288:Parenteral Nutrition / Q000379:methods*; D011182:Postoperative Care; D016482:Urinalysis
D000603:Amino Acids, Sulfur; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D008715:Methionine; D003545:Cysteine