Growth assessment in children with phenylketonuria

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

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).

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.

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.