A survey of feeding practices in infants with phenylketonuria

Background: Although the management of phenylketonuria (PKU) in infancy and early childhood is a critical part of the overall care of the disorder, there are few guidelines on infant feeding in this condition. This survey was undertaken to establish the practices of dietitians from major PKU centres in Australia and the UK. Methods: A postal questionnaire examining infant feeding practices was sent to dietitians at nine major PKU centres in the UK and four in Australia, with each dietitian describing the infant feeding process in their last five infants. A total of 63 infants were investigated. Results: A lower than expected incidence of infants with PKU were breast fed at the time of diagnosis: 28% of infants in the UK and 41% from Australia. Amino acid intake varied between 2.0 g kg^-1 day^-1 to 3.5 g kg^-1 day^-1 with 86% of dietitians calculating total amino acid intake derived from both protein substitute intake and normal infant formula. Amino acid intake was not calculated in breast-fed infants. In breast-fed infants, phenylalanine-free protein substitute was always given before breast feeds. In bottle-fed infants, normal infant formula was given before phenylalanine-free protein substitute in 75% of infants. Solids were usually introduced between 3 and 6 months and phenylalanine-free solids were given initially to the majority of infants. Most problems were seen when introducing a more concentrated phenylalanine-free protein substitute to maintain the required amino acid intake in older infants. Age of introduction varied between 4 and 12 months and type of approach included concentrating infant protein substitutes, use of L-amino acid protein substitutes only, or L-amino acid protein substitutes with added carbohydrate, vitamins and minerals. Conclusions: There appeared to be no uniform policy of infant feeding in PKU and more work is needed correlating practices to develop national and even international protocols for management.