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- Title
Glycomacropeptide in children with phenylketonuria: does its phenylalanine content affect blood phenylalanine control?
- Authors
Daly, A.; Evans, S.; Chahal, S.; Santra, S.; MacDonald, A.
- Abstract
Background In phenylketonuria ( PKU), there are no data available for children with respect to evaluating casein glycomacropeptide ( CGMP) as an alternative to phenylalanine-free protein substitutes [Phe-free L-amino acid ( AA)]. CGMP contains a residual amount of phenylalanine, which may alter blood phenylalanine control. Methods In a prospective 6-month pilot study, we investigated the effect on blood phenylalanine control of CGMP-amino acid ( CGMP- AA) protein substitute in 22 PKU subjects (13 boys, nine girls), median age (range) 11 years (6-16 years). Twelve received CGMP- AA and nine received Phe-free L- AA, (1 CGMP- AA withdrawal). Subjects partially or wholly replaced Phe-free L- AA with CGMP- AA. If blood phenylalanine exceeded the target range, the CGMP- AA dose was reduced and replaced with Phe-free L-amino acids. The control group remained on Phe-free L- AAs. Phenylalanine, tyrosine and Phe : Tyr ratio concentrations were compared with the results for the previous year. Results In the CGMP- AA group, there was a significant increase in blood phenylalanine concentrations (pre-study, 275 μmol L−1; CGMP- AA, 317 μmol L−1; P = 0.02), a decrease in tyrosine concentrations (pre-study, 50 μmol L−1; CGMP- AA, 40 μmol L−1; P = 0.03) and an increase in Phe : Tyr ratios (pre-study, Phe : Tyr 4.9:1; CGMP- AA, Phe : Tyr 8:1; P = 0.02). In the control group there was a non-significant fall in phenylalanine concentrations (pre-study 325μmol/L: study 280μmol/L [p = 0.9], and no significant changes for tyrosine or phe/tyr ratios [p = 0.9]. Children taking the CGMP-AA found it more acceptable to L-AA. Conclusions Blood phenylalanine control declined with CGMP- AA but, by titrating the dose of CGMP- AA, blood phenylalanine control remained within target range. The additional intake of phenylalanine may have contributed to the change in blood phenylalanine concentration. CGMP- AA use requires careful monitoring in children.
- Subjects
PHENYLKETONURIA treatment; AMINO acids; CASEINS; DIETARY supplements; LONGITUDINAL method; PEPTIDES; PHENYLALANINE; PROBABILITY theory; TYROSINE; PILOT projects; STATISTICAL significance; DESCRIPTIVE statistics; CHILDREN
- Publication
Journal of Human Nutrition & Dietetics, 2017, Vol 30, Issue 4, p515
- ISSN
0952-3871
- Publication type
Article
- DOI
10.1111/jhn.12438