Adult Patients with Well-Controlled Phenylketonuria Tolerate Incidental Additional Intake of Phenylalanine

Rijn, M. van; Hoeksma, Marieke; Sauer, Pieter J. J.; Modderman, P.; Reijngoud, Dirk-Jan; Spronsen, Francjan J. van

doi:10.1159/000324924

Cited by 21 publications

(14 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There is evidence to suggest that some individuals with PKU may tolerate more phenylalanine than they have been prescribed by their health professionals [8][9][10]. The only way that this can be tested is to systematically challenge individuals with additional phenylalanine.…”

Section: Establishing Maximum Phenylalanine Tolerancementioning

confidence: 99%

PKU dietary handbook to accompany PKU guidelines

MacDonald

Wegberg

Ahring

et al. 2020

Orphanet J Rare Dis

133

141

View full text Add to dashboard Cite

Background: Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. Main body: In 2017 the first European PKU Guidelines were published. These guidelines contained evidence based and/or expert opinion recommendations regarding diagnosis, treatment and care for patients with PKU of all ages. This manuscript is a supplement containing the practical application of the dietary treatment. Conclusion: This handbook can support dietitians, nutritionists and physicians in starting, adjusting and maintaining dietary treatment.

show abstract

Section: Establishing Maximum Phenylalanine Tolerancementioning

confidence: 99%

PKU dietary handbook to accompany PKU guidelines

MacDonald

Wegberg

Ahring

et al. 2020

Orphanet J Rare Dis

133

141

View full text Add to dashboard Cite

show abstract

“…In a recent study, van Rijn et al investigated the effect of an additional Phe load on blood Phe concentrations in six adult patients [24]. In this study population Phe concentrations before the study were within the target range of 120–600 μmol/l.…”

Section: Discussionmentioning

confidence: 99%

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

Grünert

Brichta

Krebs

et al. 2013

Nutr J

View full text Add to dashboard Cite

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.

show abstract

“…However, there still may be over restriction of dietary Phe intake with low Phe diets (with and without BH4 treatment). Both MacLeod et al and van Rijn et al demonstrated in 8 (not clearly well-controlled patients) and 6 (well-controlled) patients that Phe intake could increase substantially without changing the blood Phe concentrations significantly [ 190 , 195 ]. It has also been shown that Phe intake can be increased with a higher dose of Phe-free L-amino acid supplements [ 196 , 197 ].…”

Section: Dietary Treatmentmentioning

confidence: 99%

The complete European guidelines on phenylketonuria: diagnosis and treatment

Wegberg

MacDonald

Ahring

et al. 2017

Orphanet J Rare Dis

573

990

View full text Add to dashboard Cite

Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. If left untreated, PKU results in increased phenylalanine concentrations in blood and brain, which cause severe intellectual disability, epilepsy and behavioural problems. PKU management differs widely across Europe and therefore these guidelines have been developed aiming to optimize and standardize PKU care. Professionals from 10 different European countries developed the guidelines according to the AGREE (Appraisal of Guidelines for Research and Evaluation) method. Literature search, critical appraisal and evidence grading were conducted according to the SIGN (Scottish Intercollegiate Guidelines Network) method. The Delphi-method was used when there was no or little evidence available. External consultants reviewed the guidelines. Using these methods 70 statements were formulated based on the highest quality evidence available. The level of evidence of most recommendations is C or D. Although study designs and patient numbers are sub-optimal, many statements are convincing, important and relevant. In addition, knowledge gaps are identified which require further research in order to direct better care for the future.

show abstract

Adult Patients with Well-Controlled Phenylketonuria Tolerate Incidental Additional Intake of Phenylalanine

Cited by 21 publications

References 17 publications

PKU dietary handbook to accompany PKU guidelines

PKU dietary handbook to accompany PKU guidelines

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

The complete European guidelines on phenylketonuria: diagnosis and treatment

Contact Info

Product

Resources

About