Main issues in micronutrient supplementation in phenylketonuria.

For almost all patients with PKU, a low phenylalanine diet is the basis of the treatment despite a widely varying natural protein tolerance. A vitamin and mineral supplement is essential and it is commonly added to a phenylalanine-free (phe-free) source of L-amino acids. In PKU, many phe-free L-amino acid supplements have age-specific vitamin and mineral profiles to meet individual requirements. The main micronutrient sources are chemically derived and their delivery dosage is usually advised in three or more doses throughout the day. Within the EU, the composition of VM (vitamin and mineral) phe-free L-amino acid supplements is governed by the Foods for Special Medical Purposes (FSMP) directive (European Commission Directive number 1999/21/EC and amended by Directive 2006/141/EC). However the micronutrient composition of the majority fails to remain within FSMP micronutrient maximum limits per 100 kcal due to their low energy content and so compositional exceptions to the FSMP directive have to be granted for each supplement. All patients with PKU require an annual nutritional follow-up, until it has been proven that they are not at risk of any vitamin and mineral imbalances. When non-dietary treatments are used to either replace or act as an adjunct to diet therapy, the quality of micronutrient intake should still be considered important and monitored systematically. European guidelines are required about which micronutrients should be measured and the conditions (fasting status) for monitoring.

Does maternal knowledge impact blood phenylalanine concentration in Turkish children with phenylketonuria?

The aim of this study was to compare the level of maternal knowledge and the blood phenylalanine (Phe) control in phenylketonuria (PKU; OMIM 261600). The study was conducted on 144 children (81 boys, 63 girls) with PKU, aged between 1 and 15 years, at Hacettepe University Ihsan Dogramaci Children's Hospital, Metabolism and Nutrition Unit. All subjects were treated with a low-Phe diet using a Phe-exchange system. A 20-question multiple-choice questionnaire was applied to the mothers to determine their knowledge about PKU and its dietary treatment. Questions in the test consisted of the knowledge about the disease (6 questions), general dietary knowledge (14 questions) and knowledge about specific exchange within the dietary questions (6 questions). The median blood Phe concentration for the previous 3-year period was used as an indicator of metabolic control. Eighty-seven children had a median blood Phe concentration above the MRC Working Party Guidelines. There was a negative correlation between maternal knowledge about exchange and median blood Phe concentration in the child (p<0.05). Maternal knowledge about a standard 15 mg Phe exchange system is correlated with dietary compliance as measured by blood Phe concentrations in our subjects. We would like to implement an easier method of measuring Phe exchanges to improve dietary knowledge in the mothers.