Normal Growth in PKU Patients Under Low-Protein Diet in a Single-Center Cross-Sectional Study

  • Jana Matic
  • Nina A. Zeltner
  • Johannes HäberleEmail author
Research Report
Part of the JIMD Reports book series (JIMD, volume 43)


Dietary phenylalanine restriction in phenylketonuria (PKU) patients is usually mandatory in order to prevent cognitive impairment. The influence of a low-protein diet on growth has raised concerns in families and caregivers. This paper aims to investigate the growth in PKU patients treated with a low-protein diet including supplementation of amino acids and other nutrients according to standard protocols.

We performed a single-center, cross-sectional study on growth in pediatric PKU patients (n = 51) treated with low-protein diet over a 20-month period. Height of healthy siblings (n = 44) and target height, calculated based on parents’ height, served as controls.

No statistically significant differences were found comparing mean height z-scores between patients and siblings (p = 0.261). Patients <12 years showed a reduction in mean height z-scores compared to the target height (p = 0.020), whereas postpubertal patients ≥12 years did not differ significantly in height z-scores compared to the target height (p = 0.071). Healthy siblings’ height did not differ from target height in neither age group (p = 0.100/p = 0.301).

Our results suggest that PKU patients treated with low-protein diet can achieve normal growth with patients making up the leeway after puberty. While prepubertal patients were shorter than expected based on their target height, older patients were within their expected target height. This study indicates that current practice of low-protein diet in PKU patients allows normal growth.


Growth Low-protein diet Phenylketonuria PKU Target height 



We are obliged to all patients and their families who took part in this study. We would also like to thank Nathalie Wunderli and Priska Wuhrbach for their help in measuring the patients’ height. We also gratefully acknowledge the access to height percentiles elaborated by the Department of Developmental Paediatrics of the University Children’s Hospital Zurich under the direction of Prof. Dr. O. Jenni.


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Copyright information

© Society for the Study of Inborn Errors of Metabolism (SSIEM) 2018

Authors and Affiliations

  • Jana Matic
    • 1
  • Nina A. Zeltner
    • 1
  • Johannes Häberle
    • 1
    Email author
  1. 1.Division of Metabolism, and Children’s Research CenterUniversity Children’s Hospital ZurichZurichSwitzerland

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