Nutrient intake and growth of infants with phenylketonuria under-going therapy

Background: Because of reports of poor growth, a study was conducted for 6 months in 35 infants with classic phenylketonuria diagnosed during the neonatal period who were fed Phenex-1 Amino Acid Modified Medical Food With Iron (Ross Products Division, Columbus, OH, U.S.A.). as their primary protein source. Methods: Diet diaries and anthropometric measures were obtained monthly as part of a larger study in which nutrition status was evaluated. Results: In 6-month-old infants, mean percentiles for crown-heel length (59.14 +/- 4.31 SEM), head circumference (63.88 +/- 4.50) and weight (71.51 +/- 4.25) were normal. Mean (+/- SEM) daily intake of medical food was 79 +/- 4 g; protein and energy intakes were 17.3 +/- 0.6 g and 2772 +/- 75.6 W (660 +/- 18 kcal). Mean daily phenylalanine and tyrosine intakes per kilogram of body weight were 40 +/- 1 mg and 219 +/- 9 mg. Intakes of protein, energy, and tyrosine were positively correlated with crown-heel length, head circumference, and weight at 3 months of study. Overall plasma phenylalanine and tyrosine concentrations during the 6-month study were 297 +/- 41 mu mol/l and 58 +/- 5 mu mol/l, respectively. Neither plasma phenylalanine nor tyrosine concentration was correlated with growth. Conclusion: Phenex-1 supports normal growth when fed in adequate amounts. These data support those of the Medical Research Council Working Party on Phenylketonuria for 3 g/kg per day of amino acids from medical food.