Children and adolescents with phenylketonuria display fluctuations in their blood phenylalanine levels.

AIM: This study examined the impact of fluctuations in metabolic control on the intelligence quotient (IQ) of children and adolescents with early, continuously treated phenylketonuria (PKU). METHODS: This was a clinic-based study carried out at University Hospital Munster, Germany, from 2015 to 2017. We investigated 49 patients (28 boys) with early treated PKU, who were aged 6-18 years with a mean age of 11.2 ± 4.1 years. All the patients were on a continuous phenylalanine-restricted diet. Of the 49 patients, 29 (18 boys) had classic PKU and 21 patients (11 girls) had mild PKU. The patients' blood phenylalanine levels were assessed every week for 26 weeks and analysed for fluctuations, indicated by the standard deviation of the individual blood phenylalanine levels. We also assessed the concurrent Full Scale IQ (FSIQ) of the patients. RESULTS: In patients with classic PKU, FSIQ was negatively correlated with blood phenylalanine levels, but not with level fluctuations. In patients with mild PKU, FSIQ was not correlated with blood phenylalanine levels, but was negatively correlated with level fluctuations. CONCLUSION: The blood phenylalanine levels of patients with mild PKU showed minor interindividual differences, which may have allowed fluctuations to exert a negative effect on the FSIQ.

Dietary practices in propionic acidemia: A European survey.

BACKGROUND: The definitive dietary management of propionic acidaemia (PA) is unknown although natural protein restriction with adequate energy provision is of key importance. AIM: To describe European dietary practices in the management of patients with PA prior to the publication of the European PA guidelines. METHODS: This was a cross-sectional survey consisting of 27 questions about the dietary practices in PA patients circulated to European IMD dietitians and health professionals in 2014. RESULTS: Information on protein restricted diets of 186 PA patients from 47 centres, representing 14 European countries was collected. Total protein intake [PA precursor-free L-amino acid supplements (PFAA) and natural protein] met WHO/FAO/UNU (2007) safe protein requirements for age in 36 centres (77%). PFAA were used to supplement natural protein intake in 81% (n = 38) of centres, providing a median of 44% (14-83%) of total protein requirement. Seventy-four per cent of patients were prescribed natural protein intakes below WHO/FAO/UNU (2007) safe levels in one or more of the following age groups: 0-6 m, 7-12 m, 1-10 y, 11-16 y and > 16 y. Sixty-three per cent (n = 117) of patients were tube fed (74% gastrostomy), but only 22% received nocturnal feeds. CONCLUSIONS: There was high use of PFAA with intakes of natural protein commonly below WHO/FAO/UNU (2007) safe levels. Optimal dietary management can only be determined by longitudinal, multi-centre, prospective case controlled studies. The metabolic instability of PA and small patient cohorts in each centre ensure that this is a challenging undertaking.