Evaluating Therapy and Growth in Children with Phenylketonuria: A Retrospective Longitudinal Study from Two Romanian Centers

Abstract

Background and Objectives: Phenylketonuria (PKU) is a rare genetic disorder characterized by the inability to convert the essential amino acid phenylalanine into tyrosine. Early dietary treatment can successfully prevent complications, but controversies still exist regarding the attainment of normal growth in these patients. Materials and Methods: Eighteen patients with PKU from two Romanian reference centers were compared to eighteen non-PKU controls, matched for age and gender. The comparisons used weight-for-height, weight-for-age, height/length-for-age, and body mass index-for-age z-scores from birth to three years of age. Results: The PKU study group consisted of nine boys and nine girls, with a median follow-up period of thirty-six months (interquartile range = 9.75). While median values of all four growth metrics remained within the normal range across the entire study period, weight-for-age z-scores were significantly lower in PKU patients throughout most of the study (p < 0.001). Conclusions: The persistent lower weight-for-age z-scores of the PKU patients compared to controls indicate that ongoing monitoring and potential adjustments in dietary therapy may be necessary to further optimize growth outcomes.

Keywords: growth; metabolic disease; protein intake; therapy.

Figure 1

Distribution of protein sources across total protein intake.

Figure 2

Box plot comparison of weight-for-height, weight-for-age, height-for-age, and BMI-for-age z-scores between PKU patients and controls. Each box plot displays the median (central line), interquartile range (box), and whiskers, which extend to the most extreme data points within 1.5 times the interquartile range from the first and third quartiles. Circles (○) represent mild outliers (1.5–3 times the interquartile range, IQR), while asterisks (*) indicate extreme outliers (beyond 3 times the IQR).

Figure 3

Correlation analysis between growth, Phe blood levels, and dietary parameters in PKU patients. Significance levels were *** p < 0.001, ** p < 0.01, and * p < 0.05. The color gradient in the figure indicates the level of significance, where darker shades denote stronger associations and lighter shades indicate relatively lower statistical significance.