RECOMMENDATIONS FOR PROTEIN AND ENERGY INTAKES BY PATIENTS WITH PHENYLKETONURIA

Recent reports describe poor growth in treated children with phenylket onuria (PKU). That poor growth is not a concomitant of the disorder an d need not result from therapy is demonstrated by data from the U.S.A. PKU Collaborative Study and from recent data from the U.S.A. In these studies, sufficient protein equivalent was supplied by medical food c ontaining either a low phenylalanine (Phe) casein hydrolysate or Phe-f ree L-amino acids. Protein and energy intakes of infants and children with PKU who grew well are compared to intakes of normal North America n child;en. Factors that influence nitrogen (N) requirements include: state of health, energy intake, the form in which N is administered an d the size of the dose. Failure to prevent poor growth in childhood ma y lead to a stunted adult [13] who is at risk for obesity. The use of actual body weight as a basis for calculating protein and energy requi rements is appropriate only when the child is growing normally. Based on experience with PKU in the U.S.A., the following are recommended: ( 1) a protocol that prescribes a range for Phe, protein, and energy for infants and children should be developed; (2) adequate protein equiva lent to cover N losses due to poor utilization of amino acids and prot ein hydrolysates should be prescribed; (3) medical food should be admi nistered in several doses throughout the day; (4) a source of Phe shou ld be fed with the medical food; (5) adequate energy should be prescri bed to prevent excess use of amino acid for energy purposes; (6) nutri tion support during illness should be appropriate to help prevent musc le protein catabolism with attendant elevated plasma Phe.