Growth assessment in children with phenylketonuria.

Objectives: To investigate the growth parameters of children with phenylketonuria and assess the impact of a phenylalanine-restricted diet on their physical development.

Methods: The study involved 39 children diagnosed with phenylketonuria through newborn screening at the Central Child Teaching Hospital, Baghdad, Iraq. Data were collected during scheduled monthly check-ups, including phenylalanine levels, diet compliance, and anthropometric measurements. The children were divided into two groups based on their phenylalanine levels during the 3-year follow-up period: well-controlled group (average phenylalanine level of less than 360 μmol/L, with no single reading exceeding 600 μmol/L; n=14) and poorly-controlled group (one or more phenylalanine readings above 600 μmol/L during the follow-up period; n=25).

Results: The mean height readings for all time points (at birth and 3, 6, 9, 12, 15, 18, 21, 24 and 36 months of age) were higher in the well-controlled group than the poorly-controlled group, however, only at 3 months of age the difference was statistically significant. Height Z-scores revealed a clearer pattern: although the poorly-controlled group had higher height Z-scores at birth (P=0.001), the well-controlled group showed significantly higher height Z-scores at 3, 6, 12, 15, 18, 24, and 36 months (P<0.05). The well-controlled group exhibited significantly higher mean weight measurements compared to the poorly-controlled group at 3, 6, 9, 15, 18 months and 21 months (P<0.05). From 6 to 36 months, the well-controlled group consistently had significantly higher weight Z-scores than the poorly-controlled group (P<0.05). The well-controlled group showed more favorable height and weight Z-score distributions at 36 months of age compared to the poorly-controlled group, but the differences were not statistically significant (P>0.05). Both groups had height and weight Z-scores within the normal range at 36 months of age.

Conclusions: The children with phenylketonuria who receive good dietary control show better improvements in growth parameters compared to those with poor dietary control, however, both groups maintain height and weight Z-scores within the normal range, indicating generally adequate physical development across the cohort.