Excess weight among children with phenylketonuria.

Children with phenylketonuria (PKU) participating in the PKU Collaborative Study were found to be overweight on average by age 4, particularly the girls. A search was made for factors that were most highly associated with a child's overweight status at age 4, in order to help understand the etiology of the problem, as well as to help predict who would be at highest risk of becoming overweight by 4 years. For the analyses, the PKU children who were above the 93rd percentile of weight for their height and sex at age 4 were classified as overweight, and this group was compared to the normal weight PKU children. Among scores of variables measured on the 151 children during their first 2 years of life, overweight (excess weight for height) at 24 months was the best predictor of overweight status at 4 years. Other probable risk factors of being overweight at 4 years were lower socioeconomic status (for both sexes) and overweight parents and large stature (for the girls only). Factors that were not significantly related to overweight status included the level of restriction of the diet therapy for PKU, energy intake during the first 4 years of life, and the diet composition (protein/energy ratio).