Physical growth in phenylketonuria: II. Growth of treated children in the PKU collaborative study from birth to 4 years of age.

Height, weight, and head circumference data up to age 4 years are reported for 124 children with phenylketonuria (PKU) who had been started on diet management before 4 months (121 days) of age and who were participating in the Collaborative Study of Children Treated for Phenylketonuria. Growth measurements of both the children and their parents corresponded with national and international standards. The growth of children with PKU was compared also with that of a group of normal children in the United States in whom corresponding longitudinal growth data had been obtained at the Fels Research Institute (FRI). Statistically significant differences betweeen the groups were not noted at any age. However, when these groups were compared on coefficients using curve fitting, a trend toward a greater increase in weight as they became older, noted in both sexes in the PKU study group, was significantly higher (P less than .005) in the PKU study girls compared with the FRI sample. Height growth was identical in both groups, and comparison with family data showed that the children with PKU grew as expected for their genetic endowment.