The Effects of Breastfeeding in Infants With Phenylketonuria.

PURPOSE: In the early years of phenylketonuria (PKU) treatment, mothers and healthcare professionals often decide to discontinue breastfeeding after the diagnosis of PKU in infants. It was believed to be the only effective way to monitor the infant's intake and allow for precise titration and measurement of the intake of phenylalanine (Phe). In the early 1980s, with the determination of low concentration of Phe in breast milk, breast milk supplemented with Phe-free formula has become an acceptable dietary treatment for infants with PKU. Today, breastfeeding is encouraged and well established in PKU patients. The aim of the present study is to investigate the prevalence and duration of breastfeeding, the effect of breastfeeding on serum Phe levels, and weight gain in infants with PKU. DESIGN AND METHODS: Data were collected from chart reviews. Medical records of 142 children with PKU diagnosed via the national neonatal screening program were analyzed retrospectively. RESULTS: Of the 41 infants with complete medical records, 40 (97.6%) were breastfed following delivery whereas only one (2.4%) was bottle fed. After the diagnosis, breastfeeding was continued in 25 (61%) infants with phenylalanine-free amino acid based protein substitute. The mean duration of breastfeeding was 7.4±4.0 (1-15) months. Serum Phe concentration of breastfed infants (280±163 µmol/L) was significantly lower than non-breastfed infants (490±199 µmol/L) (p<0.001). Mean monthly weight gain in the first year of life was significantly higher in breastfed patients (493±159 g/month) compared to non-breastfed patients (399±116 g/month) (p=0.046). CONCLUSION: In the first year of life, weight gain and serum Phe levels were more favorable in breastfed infants with PKU compared to non-breastfed infants with PKU.