Phenylalanine Free Infant Formula in PKU
Research type
Research Study
Full title
Phenylalanine Free Infant Formula in Patients with Phenylketonuria: A Retrospective Study
IRAS ID
325952
Contact name
Anita MacDonald
Contact email
Sponsor organisation
Birmingham Women's and Children's Hospital
Duration of Study in the UK
1 years, 0 months, 1 days
Research summary
Research Summary
In infants with phenylketonuria (PKU), dietary management consists of restricting natural protein intake and supplementing this with phenylalanine-free amino acid based infant formula. Phenylalanine-free infant formula is an essential source of safe protein in a phenylalanine restricted diet, but data on their long-term efficacy and use are lacking. We aim to conduct a single-center, retrospective study to evaluate the growth, dietary intake, and metabolic control of infants prescribed phenylalanine-free amino acid-based infant formula (PKU Start: Vitaflo).
Summary of Results
Sponsor: Birmingham Women’s and Children’s NHS Foundation Trust
Funding: N/A – carried out as part of standard clinical dietetic practice Competing Interests: non declared Location of study: Birmingham Children’s HospitalBackground: In infants with phenylketonuria (PKU), dietary management consists of restricting natural protein intake (breast milk or standard infant formula) and supplementing this with phenylalanine-free amino acid based infant formula. Phenylalanine-free infant formula is an essential source of safe protein in a phenylalanine restricted diet, but data on their long-term efficacy and use are lacking. This single-centre, retrospective study aimed to assess the growth, dietary intake, metabolic control and experience of infants prescribed phenylalanine-free infant amino acid-based formula (PFIAA) (PKU Start: Vitaflo International Ltd).
Methods: Data on blood phenylalanine concentrations, growth (weight and length/height, body mass index (BMI)), dietary intake, and tolerance were collected retrospectively from patient medical notes from diagnosis until 2 years of age. Parents also completed a questionnaire on their child's feeding practices and experiences with PFIAA.
Results: 25 children (12 males, 48%) with a median age of 3.2 years (range: 1.6-5.9 years) were included. 20 (80%) discontinued the formula at a median age of 1.7years, while 5 (20%) continued to receive some formula until a median age of 3.2 tears. By one year of age, 56% (n=14) of the children had stopped night feeding.
Median blood phenylalanine levels were within the target range of 120-360 µmol/L. Normal growth was observed from 0 to 24 months of age. No significant differences in weight, length, and BMI-for-age z-scores were found between males and females, between PFIAA discontinuation before or after 24 months, or between night feed discontinuation before or after 12 months.
Median energy intake (food and formula) as a percentage of the estimated average requirements (EAR) was 116% at 6 months and 109% at 24 months of age. The median percentage of energy intake from PFIAA decreased from 65% at age 6 months, to age 36% at 12 months. At 24 months, 60% (n=15) of children completely stopped using PFIAA, 8% (n=2) used a small amount (contributing <10% of total energy intake), and 32% (n=8) still had a median of 33% of their total energy intake from PFIAA.
Median total protein intake increased from 2.8 g/kg/day at 6 months to 3.3 g/kg/day at 24 months, with natural protein intake remaining stable at 0.4 g/kg/day. PFIAA provided a median of 74% of total protein intake at 0-6 months, decreasing to 32% at 7-12 months and 23% at 13-18 months.
PFIAA was well accepted by 80% of infants, with 20% experiencing initial feeding difficulties. Infant feeding difficulties (28%, n=7) and gastrointestinal symptoms (52%, n=13) were most common at age 0-6 months, while respiratory symptoms (16%, n=4) and infectious diseases (60%, n=15) were most common at age 7-12 months but decreased with time. Constipation was reported at age 0-6 months in 44% (n=11) of infants but improved over time. Vomiting, usually associated with infections, occurred in all age groups. Some infants had reflux (n=5, 20%) during follow-up, but this was not attributed to the study formula.
Conclusion: In infants/children with PKU, the PFIAA was well accepted and tolerated with good metabolic control, and normal growth. Continued monitoring of the use of PFIAA and ensuring timely discontinuation and transition to age-appropriate formulas is important for optimizing PKU dietary management.
Results of this study will be published in a peer review journal.
Has the registry been updated to include summary results?: No
If yes - please enter the URL to summary results:
If no – why not?: N/A
Did you follow your dissemination plan submitted in the IRAS application form (Q A51)?: Pending
If yes, describe or provide URLs to disseminated materials:
If pending, date when dissemination is expected: 01/12/2023
If no, explain why you didn't follow it:
Have participants been informed of the results of the study?: Pending
If yes, describe and/or provide URLs to materials shared and how they were shared:
If pending, date when feedback is expected: 01/12/2023
If no, explain why they haven't:
Have you enabled sharing of study data with others?: No
If yes, describe or provide URLs to how it has been shared:
If no, explain why sharing hasn't been enabled: Study data and results will be available via a published paper in a peer reviewed journal.
Have you enabled sharing of tissue samples and associated data with others?: No
If yes, describe or provide a URL:
If no, explain why: N/AREC name
Wales REC 3
REC reference
23/WA/0143
Date of REC Opinion
5 May 2023
REC opinion
Further Information Favourable Opinion