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Changes in serum phenylalanine after overnight fasts in youngsters with phenylketonuria
Author(s) -
Ferguson C.,
Morris A. M.
Publication year - 1999
Publication title -
journal of human nutrition and dietetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.951
H-Index - 70
eISSN - 1365-277X
pISSN - 0952-3871
DOI - 10.1046/j.1365-277x.1999.00158.x
Subject(s) - bedtime , medicine , phenylalanine , endocrinology , amino acid , biochemistry , chemistry
Summary Background and aims : In patients with phenylketonuria (PKU), overnight fasting is associated with rises in serum phenylalanine (PHE) concentration. This is thought to result from catabolism of endogenous protein, which can be reduced by a bedtime snack accompanied by a dose of PHE‐free protein substitute (P/S). This study assessed the effectiveness of this strategy and whether any additional benefit was conferred by omitting PHE from the bedtime snack. Methods : Data are presented for 18 PKU children (aged 9–16 years), studied over a 48‐h period whilst following diets of known composition. All the subjects had a bedtime snack accompanied by 25% of their P/S daily requirement. Half the subjects (Group X) had 25% of their daily PHE allowance in the bedtime snack, whilst the others (Group Z) ate only ‘PHE‐free’ foods at this time. Results : Overnight changes in serum PHE levels were generally small for both groups; the mean serum PHE level changed very little overnight (Group X: 405 μmol L −1 post snack, 389 μmol L −1 prebreakfast; Group Z: 430 μmol L −1 post snack, 426 μmol L −1 pre breakfast). Conclusion : Overnight changes in serum PHE levels can be minimized by a bedtime snack accompanied by a proportion of the daily protein substitute. Omission of PHE from the snack confers no extra advantage.