Satisfaction with home blood sampling methods and expectations for future point-of-care testing in phenylketonuria: Perspectives from patients and professionals.

INTRODUCTION: Phenylketonuria (PKU) requires regular phenylalanine monitoring to ensure optimal outcome. However, home sampling methods used for monitoring suffer high pre-analytical variability, inter-laboratory variability and turn-around-times, highlighting the need for alternative methods of home sampling or monitoring. METHODS: A survey was distributed through email and social media to (parents of) PKU patients and professionals working in inherited metabolic diseases in Denmark, The Netherlands, and United Kingdom regarding satisfaction with current home sampling methods and expectations for future point-of-care testing (POCT). RESULTS: 210 parents, 156 patients and 95 professionals completed the survey. Countries, and parents and patients were analysed together, in absence of significant group differences for most questions. Important results are: 1) Many patients take less home samples than advised. 2) The majority of (parents of) PKU patients are (somewhat) dissatisfied with their home sampling method, especially with turn-around-times (3-5 days). 3) 37% of professionals are dissatisfied with their home sampling method and 45% with the turn-around-times. 4) All responders are positive towards developments for POCT: 97% (n = 332) of (parents of) patients is willing to use a POC-device and 76% (n = 61) of professionals would recommend their patients to use a POC-device. 5) Concerns from all participants for future POC-devices are costs/reimbursements and accuracy, and to professionals specifically, accessibility to results, over-testing, patient anxiety, and patients adjusting their diet without consultation. CONCLUSION: The PKU community is (somewhat) dissatisfied with current home sampling methods, highlighting the need for alternatives of Phe monitoring. POCT might be such an alternative and the community is eager for its arrival.

Dietary treatment in Dutch children with phenylketonuria: An inventory of associated social restrictions and eating problems.

OBJECTIVES: Dietary treatment in phenylketonuria (PKU) is known to cause eating problems, but knowledge of both prevalence and magnitude, especially for social restrictions, is scarce. Our aim was to evaluate the social restrictions and eating problems that children with PKU and their caregivers experience with dietary treatment. METHODS: A web-based questionnaire, based on the Behavioral Pediatrics Feeding Assessment Scale with additional PKU-specific questions, was developed in close collaboration with and distributed by the Dutch PKU Association, which sent an e-mail to its members containing a link to the questionnaire. The questionnaire was completed by caregivers of children with PKU in the Netherlands and caregivers of age-matched children without PKU. Data were analyzed with the Kruskal-Wallis and Mann-Whitney U test using SPSS. RESULTS: Compared with caregivers of children in the control group (ages 1-16 y; n = 50), caregivers of children with PKU (ages 1-16 y; n = 57) reported more difficulty in offering food variety, experienced more stress when eating an evening meal outside the home and during vacation, and were stricter about (accidental) spilling of food during dinner by the child (P < 0.05). They also reported to being angrier, more frustrated, and more anxious when feeding their child, and they more often felt that their child's eating pattern had a negative influence on the child's general health (P < 0.05). CONCLUSION: This pilot study provides further evidence that restriction of social activities and eating problems associated with dietary restrictions is more common in children with PKU, and warrants awareness on this topic among professionals working with these children.

Aspartame and Phe-Containing Degradation Products in Soft Drinks across Europe.

Phenylketonuria and tyrosinemia type 1 are treated with dietary phenylalanine (Phe) restriction. Aspartame is a Phe-containing synthetic sweetener used in many products, including many 'regular' soft drinks. Its amount is (often) not declared; therefore, patients are advised not to consume aspartame-containing foods. This study aimed to determine the variation in aspartame concentrations and its Phe-containing degradation products in aspartame-containing soft drinks. For this, an LC-MS/MS method was developed for the analysis of aspartame, Phe, aspartylphenylalanine, and diketopiperazine in soft drinks. In total, 111 regularly used soft drinks from 10 European countries were analyzed. The method proved linear and had an inter-assay precision (CV%) below 5% for aspartame and higher CVs% of 4.4-49.6% for the degradation products, as many concentrations were at the limit of quantification. Aspartame and total Phe concentrations in the aspartame-containing soft drinks varied from 103 to 1790 µmol/L (30-527 mg/L) and from 119 to 2013 µmol/L (20-332 mg/L), respectively, and were highly variable among similar soft drinks bought in different countries. Since Phe concentrations between drinks and countries highly vary, we strongly advocate the declaration of the amount of aspartame on soft drink labels, as some drinks may be suitable for consumption by patients with Phe-restricted diets.