Breast-feeding in the management of the newborn with phenylketonuria: a practical approach to dietary therapy.

Guidelines introduced in 1979 for breast-feeding infants with phenylketonuria included a formula containing low amounts of phenylalanine (PHE) as part of the dietary prescription. Although the guidelines were revised in 1988, new PHE-free products were not included. In addition, the guidelines recommend infant weight checks before and after feeding to ensure correct dietary intake of breast milk. In this study, we present data based on treatment of 13 infants for the first 6 months of life using a PHE-free product and human milk (n = 9) or commercial formula (n = 4). The study began with nine breast-fed infants; five were weaned before 6 months of age and were discontinued from the study. Published estimates of volume and energy of daily human milk consumption were used to prescribe and assess intake of breast milk. No differences were noted between the groups in blood levels of PHE at initiation of dietary therapy, age at initiation of dietary therapy, or length of time to achieve metabolic control. Furthermore, blood levels of PHE and growth parameters for each month up to 6 months of age were similar for both groups. These data support the efficacy of PHE-free formula and estimation of breast milk volumes in managing the diet of infants with phenylketonuria.