Breastfeeding in the treatment of children with phenylketonuria.

OBJECTIVE To evaluate the effect of breastmilk as a source of phenylalanine (phe) on levels of this amino acid and on growth in phenylketonuric infants. METHODS The study recruited 35 breastfed phenylketonuric infants and compared their results with those of 35 infants fed on commercial, milk-based formula. The groups were paired for sex and age at weaning from breastfeeding. Data were analyzed up until cessation of breastmilk or for 12 months' follow-up. The breastfed group were given a "special formula" free of phe, by bottle every 3 hours, and breastmilk at will during the intervals. Levels of phe in the blood, collected weekly up to 6 months and fortnightly up to 1 year de age, were analyzed while breastfeeding continued. The two groups were compared in terms of the time taken for the levels of phe in blood to return to normal after treatment was started, using the Wilcoxon test. Anthropometric data were compared with Student's t paired test in the form of z scores. The phe assays were analyzed throughout breastfeeding. RESULTS The median time taken for phe levels to return to normal was 8 days for the breastfed group and 7 days for the control group. The phe assay results were normal in 87% of tests for the breastfed group and in 74.4% for the control group. The majority of children in both groups exhibited a z score > -2 on anthropometric examination. CONCLUSIONS Continuation of breastfeeding, during the treatment, proved adequate for metabolic control and growth in children with phenylketonuria.