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Dietary protein counting as an alternative way of maintaining metabolic control in phenylketonuria.

ABSTRACT: OBJECTIVE:To compare a gram protein exchange system (1g=50-mg Phenylalanine) with a unit exchange system (1unit=15-mg Phenylalanine) and its effect on the blood Phenylalanine (Phe) levels and acceptance in the dietary management for children and adolescents with Phenylketonuria. METHODS:In Phase One, participants were randomised to continue counting Phe unit exchanges (n=8) or changed to counting gram protein exchanges (n=10), using a new diet chart developed in-house. Foods containing less than 20mg Phe per serve were now considered "free." Interim data analysis confirmed no significant deterioration in Phe levels of the study group and the control group was changed to protein counting.In Phase Two, 18 participants were educated to use an updated version of the in-house diet chart - in this version foods containing less than 50mg Phe per serve were considered "free."In both phases, attitudes to PKU and its management were evaluated at baseline and 6months. Phenylalanine and tyrosine levels were measured from filter paper blood spots by tandem mass spectrometry. RESULTS:Phase One: Phe levels over 6months were comparable to pre-study levels (mean Phe pre 366?mol/L+/- 169, mean Phe post change=388?mol/L+/- 160).Phase Two: Four participants had a significant improvement in blood Phe levels, nine showed no significant change and one participant's levels were significantly higher. There was incomplete data on four participants. All participants preferred the freer diet chart. CONCLUSION:Protein exchanges (foods containing less than 50mg Phe/serve uncounted) are an alternative method of measuring Phe intake in the dietary management of Phenylketonuria.

SUBMITTER: Sweeney AL

PROVIDER: S-EPMC3509851 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Dietary protein counting as an alternative way of maintaining metabolic control in phenylketonuria.

Sweeney A L AL Roberts R M RM Fletcher J M JM

JIMD reports 20110916

<h4>Objective</h4>To compare a gram protein exchange system (1g=50-mg Phenylalanine) with a unit exchange system (1unit=15-mg Phenylalanine) and its effect on the blood Phenylalanine (Phe) levels and acceptance in the dietary management for children and adolescents with Phenylketonuria.<h4>Methods</h4>In Phase One, participants were randomised to continue counting Phe unit exchanges (n=8) or changed to counting gram protein exchanges (n=10), using a new diet chart developed in-house. Foods conta ...[more]

PMID: 23430885

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Project description:BackgroundInsufficient metabolic control during pregnancy of mothers with phenylketonuria (PKU) leads to maternal PKU syndrome, a severe embryo-/fetopathy. Since maintaining or reintroducing the strict phenylalanine (Phe) limited diet in adults with PKU is challenging, we evaluated the most important dietary and psychosocial factors to gain and sustain good metabolic control in phenylketonuric women throughout pregnancy by a questionnaire survey with 38 questions concerning therapy feasibility. Among them, the key questions covered 5 essential items of PKU care as follows: General information about maternal PKU, PKU training, diet implementation, individual metabolic care, personal support. In addition, all participating PKU mothers were asked to estimate the quality of their personal metabolic control of the concluded pregnancies. 54 PKU mothers with 81 pregnancies were approached at 12 metabolic centers in Germany and Austria were included. According to metabolic control, pregnancies of PKU women were divided in two groups: group "ideal" (not more than 5% of all blood Phe concentrations during pregnancy > 360 µmol/l; n = 23) and group "suboptimal" (all others; n = 51).ResultsThe demand for support was equally distributed among groups, concerning both amount and content. Personal support by the direct social environment (partner, family and friends) ("suboptimal" 71% vs "ideal" 78%) as well as individual metabolic care by the specialized metabolic center (both groups around 60%) were rated as most important factors. The groups differed significantly with respect to the estimation of the quality of their metabolic situation (p < 0.001). Group "ideal" presented a 100% realistic self-assessment. In contrast, group "suboptimal" overestimated their metabolic control in 53% of the pregnancies. Offspring of group "suboptimal" showed clinical signs of maternal PKU-syndrome in 27%.ConclusionThe development of training programs by specialized metabolic centers for females with PKU in child bearing age is crucial, especially since those mothers at risk of giving birth to a child with maternal PKU syndrome are not aware of their suboptimal metabolic control. Such programs should provide specific awareness training for the own metabolic situation and should include partners and families.

Project description:BackgroundPatients with phenylketonuria (PKU) have to follow a lifelong phenylalanine restricted diet. This type of diet markedly reduces the intake of saturated and unsaturated fatty acids especially long chain polyunsaturated fatty acids (LC-PUFA). Long-chain saturated fatty acids are substrates of mitochondrial fatty acid oxidation for acetyl-CoA production. LC-PUFA are discussed to affect inflammatory and haemostaseological processes in health and disease. The influence of the long term PKU diet on fatty acid metabolism with a special focus on platelet eicosanoid metabolism has been investigated in the study presented here.Methodology/principal findings12 children with PKU under good metabolic control and 8 healthy controls were included. Activated fatty acids (acylcarnitines C6-C18) in dried blood and the cholesterol metabolism in serum were analyzed by liquid chromatographic tandem mass spectrometry (LC-MS/MS). Fatty acid composition of plasma glycerophospholipids was determined by gas chromatography. LC-PUFA metabolites were analyzed in supernatants by LC-MS/MS before and after platelet activation and aggregation using a standardized protocol. Patients with PKU had significantly lower free carnitine and lower activated fatty acids in dried blood compared to controls. Phytosterols as marker of cholesterol (re-) absorption were not influenced by the dietary fatty acid restriction. Fatty acid composition in glycerophospholipids was comparable to that of healthy controls. However, patients with PKU showed significantly increased concentrations of y-linolenic acid (C18:3n-6) a precursor of arachidonic acid. In the PKU patients significantly higher platelet counts were observed. After activation with collagen platelet aggregation and thromboxane B(2) and thromboxane B(3) release did not differ from that of healthy controls.Conclusion/significanceLong-term dietary fatty acid restriction influenced the intermediates of mitochondrial beta-oxidation. No functional influence on unsaturated fatty acid metabolism and platelet aggregation in patients with PKU was detected.

Dataset Information

Dietary protein counting as an alternative way of maintaining metabolic control in phenylketonuria.

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Dietary protein counting as an alternative way of maintaining metabolic control in phenylketonuria.

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