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European Journal of Pediatrics

, Volume 153, Issue 7, pp 501–503 | Cite as

Dependence of the utilization of a phenylalanine-free amino acid mixture on different amounts of single dose ingested. A case report

  • M. -E. Herrmann
  • H. G. Brösicke
  • M. Keller
  • E. Monch
  • H. Helge
Metabolic Diseases Original Paper

Abstract

For patients with phenylketonuria the daily ingested phenylalanine-free amino acid mixture is the most important source of nitrogen. It is recommended to ingest one third of the total amount combined with main meals. Some patients, especially the older ones, do not follow this recommendation; they ingest the entire daily amount of amino acid mixture in one portion. This intake mode leads to an increased oxidative utilization of the amino acids. To set up an example for this metabolic phenomenon, a13C-leucine breath test was performed in one female phenylketonuric patient. She ingested a third of her daily amount of the amino acid mixture combined with an oral tracer of 3 mg13C-leucine/kg body weight at breakfast. The breath test was carried out by a standardized time schedule over 5 h. Three days later the breath test was repeated when she ingested the total amount of amino acid mixture in only one portion at breakfast. Total daily caloric intake and food composition were not changed. On both days a 24 h urine was collected to determine total nitrogen loss. The13C-content of expired air was analysed by gas isotope ratio mass spectrometry, the total nitrogen content was determined using a combustion unit. The13C-elimination rate as a percentage of the applied13C-tracer was 9.5% on the first test day as compared to 19.6% on the 2nd day. The corresponding total nitrogen excretion was increased (4.3–6.9 g/24 h). This single case study showed the expected results and confirmed the hypothesis that the ingestion of high amounts of amino acid mixtures is accompanied by a significantly increased oxidative utilization.

Key words

Phenylketonuria Dietary management 13C-leucine 

Abbreviations

AAM

amino acid mixture

PKU

phenylketonuria

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References

  1. 1.
    Adibi SA, Stank RT, Morse EL (1982) Modulation of leucine oxidation and turnover by graded amounts of carbohydrate intake in obese subjects. Metabolism 31:578–588CrossRefPubMedGoogle Scholar
  2. 2.
    Batterham ES, Bayley HS (1989) Effect of frequency of feeding of diets containing free or bound lysine on the oxidation of14C-lysine or14C-phenylalanine by growing pigs. Br J Nutr 62:647–655PubMedGoogle Scholar
  3. 3.
    Harper AE, Benevenga NJ, Wohlhueter RM (1970) Effect of ingestion of disproportionate amounts of amino acids. Physiol Rev 50:428–558PubMedGoogle Scholar
  4. 4.
    Krebs HA, Hems R, Lund P (1973) Some regulatory mechanisms in the synthesis of urea in the mammalian liver. Adv Enzyme Regul 11:361–377CrossRefPubMedGoogle Scholar
  5. 5.
    Raforth RJ, Onstad GR (1975) Urea synthesis after oral protein loading in man. J Clin Invest 56:1170–1174PubMedGoogle Scholar
  6. 6.
    Schadewaldt P, Brösicke H, Haisch M, Matthiesen U, Wendel U (1994) Leucine oxidation in vivo: Inter- and intraindividual variation in healthy subjects as assessed by oral L-[1-13C]leucine loads. IsotopenpraxisGoogle Scholar
  7. 7.
    Wolfe RR (1992) Radioactive and stabile isotope tracers in biomedicine. Wiley-Liss, New YorkGoogle Scholar
  8. 8.
    Young VR, Pellet PI, Bier DM (1989) A theoretical basis for increasing current estimates of the amino acid requirement in adult men with experimental support. Am J Clin Nutr 50:80–92PubMedGoogle Scholar

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • M. -E. Herrmann
    • 1
  • H. G. Brösicke
    • 1
  • M. Keller
    • 1
  • E. Monch
    • 1
  • H. Helge
    • 1
  1. 1.KAVH, KinderklinikUniversitätsklinikum Rudolf VirchowBerlinGermany

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