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Growth and skeletal maturation in children with phenylketonuria
F Schaefer1, P Burgard, U Batzler
1University Children's Hospital, Heidelberg, Germany.
Insights
Phenylketonuria (PKU) treatment in children showed moderate growth retardation in the first two years, particularly in boys, with some recovery later. Early head growth predicts cognitive development.
Area of Science:
- Pediatrics
- Metabolic Disorders
- Developmental Biology
Background:
- Phenylketonuria (PKU) is a genetic disorder requiring lifelong dietary management.
- Growth and neurodevelopmental outcomes in treated PKU patients are critical areas of study.
Purpose of the Study:
- To evaluate growth and skeletal maturation in children treated for PKU.
- To investigate the relationship between early growth parameters and later cognitive abilities.
Main Methods:
- Longitudinal study of 82 children treated for PKU, recording height, weight, head circumference, and bone age up to 6 years.
- Cognitive assessment (IQ) at 5-6 years compared to healthy controls.
- Analysis of correlations between growth parameters, phenylalanine levels, and cognitive outcomes.
Main Results:
- Moderate growth retardation observed in the first two years, more pronounced in boys, with subsequent partial recovery.
- Head circumference SDS decreased in boys during the first year, with early head size predicting cognitive abilities.
- No correlation found between phenylalanine intake/levels and growth or skeletal maturation rates.
- Mean verbal and performance IQ did not differ from controls, but smaller head circumference at 2 years was linked to poorer cognitive outcomes.
Conclusions:
- Despite adequate weight gain, PKU treatment can lead to temporary growth deceleration in early childhood.
- Early head growth is a significant predictor of cognitive development in children with PKU.
- Monitoring head circumference in infancy may help identify children at risk for cognitive deficits.
Abstract:
Growth and skeletal maturation was evaluated in 82 children participating in the German Collaborative Study of Children Treated for Phenylketonuria (PKU). Height, weight, head circumference and bone age were recorded at regular intervals for the first 6 years of life. The mean SD score (SDS) for height was not significantly different from zero at study entry, but decreased mainly during the second year of life to a nadir of -0.78 in boys and -0.54 in girls at 2.5 years. During the subsequent years, a significant trend towards a regain of height SDS was noted in both sexes. Weight-for-height SDS was close to zero in both sexes, with a significant continuous increasing trend throughout the observation period. Head circumference SDS decreased in boys during the first year of life from -0.28 to -0.68, whereas girls showed only a minor change. During the further follow-up period, head circumference SDS remained at approximately -0.3 in boys and 0.0 in girls. While the mean verbal and performance IQ of the total study population at 5 and 6 years of age did not differ from a group of 212 healthy non-PKU children, patients with a head circumference SDS less than the population median at 2 years of age exhibited poorer cognitive abilities at school age than those patients with a relative head size greater than the population median. The children with a head circumference less than the median at 2 years had smaller head sizes already at birth; in addition, the change in relative head size during the first 2 years was correlated significantly with cognitive abilities at school age in boys. Mean bone age was identical to chronological age at each time point of observation. The rate of maturation was one year of bone age per year of chronological age. No correlation between phenylalanine intake or phenylalanine concentrations and the rates of body or head growth or skeletal maturation could be established. We conclude that despite adequate weight gain, moderate growth retardation occurred during the first 2 years of life in this group of children treated for PKU. Growth was more compromised in boys than in girls and tended to be compensated during later follow-up. Early infantile head circumference and growth appear to be predictors of cognitive development.