Diurnal variation of phenylalanine and tyrosine concentrations in adult patients with phenylketonuria: subcutaneous microdialysis is no adequate tool for the determination of amino acid concentrations

Nutrition Journal

Research

Andreas Krebs¹  K Otfried Schwab¹  Sarah C Grünert¹  Jörn Oliver Sass²  Corinna M Brichta³  Klaus Hennighausen⁴  Christian Fleischhaker⁴  Hans-Willi Clement⁴  Reinhold Rauh⁴ 

[1] Center for Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg, Germany;Center for Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg, Germany;Clinical Chemistry and Biochemistry, University Children’s Hospital Zürich, Zürich, Switzerland;Center for Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg, Germany;Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany;Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany;

关键词: Phenylketonuria;    Phenylalanine;    Tyrosine;    Diurnal variation;    Diet;    Physical exercise;    Microdialysis;    Dried blood spot;    Ergometry;   

DOI  :  10.1186/1475-2891-12-60

 received in 2013-02-12, accepted in 2013-05-07,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundMetabolic control and dietary management of patients with phenylketonuria (PKU) are based on single blood samples obtained at variable intervals. Sampling conditions are often not well-specified and intermittent variation of phenylalanine concentrations between two measurements remains unknown. We determined phenylalanine and tyrosine concentrations in blood over 24 hours. Additionally, the impact of food intake and physical exercise on phenylalanine and tyrosine concentrations was examined. Subcutaneous microdialysis was evaluated as a tool for monitoring phenylalanine and tyrosine concentrations in PKU patients.MethodsPhenylalanine and tyrosine concentrations of eight adult patients with PKU were determined at 60 minute intervals in serum, dried blood and subcutaneous microdialysate and additionally every 30 minutes postprandially in subcutaneous microdialysate. During the study period of 24 hours individually tailored meals with defined phenylalanine and tyrosine contents were served at fixed times and 20 min bicycle-ergometry was performed.ResultsSerum phenylalanine concentrations showed only minor variations while tyrosine concentrations varied significantly more over the 24-hour period. Food intake within the patients’ individual diet had no consistent effect on the mean phenylalanine concentration but the tyrosine concentration increased up to 300% individually. Mean phenylalanine concentration remained stable after short-term bicycle-exercise whereas mean tyrosine concentration declined significantly. Phenylalanine and tyrosine concentrations in dried blood were significantly lower than serum concentrations. No close correlation has been found between serum and microdialysis fluid for phenylalanine and tyrosine concentrations.ConclusionsSlight diurnal variation of phenylalanine concentrations in serum implicates that a single blood sample does reliably reflect the metabolic control in this group of adult patients. Phenylalanine concentrations determined by subcutaneous microdialysis do not correlate with the patients’ phenylalanine concentrations in serum/blood.

【 授权许可】

Unknown   
© Grünert et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.