Phenylalanine tolerance and neurological outcome of children with PKU in Egypt: a single center study

Background Phenylketonuria (PKU) is considered the commonest avoidable cause of mental retardation. After newborn screening (NBS) for PKU, children with PKU are diagnosed and treated early. Untreated or late-treated cases can have neurological abnormalities. The present study aims to offer dietary management for children with PKU attending the metabolic clinic, determine their phenylalanine tolerance, and follow up of these children.Methods Thirty-six children with an established diagnosis of PKU were enrolled in the study: 31 were early-treated, and 5 were late-treated. All of them underwent baseline laboratory investigations, including the mean phenylalanine level before starting dietary management. As dietary management began, daily dietary phenylalanine levels were calculated according to the mean lifetime phenylalanine levels. Neurological outcomes and IQ were assessed after 3 years of follow-upResults A significant inverse relationship was observed between dietary phenylalanine intake and lifetime phenylalanine levels in early-treated and total cases (p = 0.003 and p < 0.001, respectively). There was a significant negative correlation between lifetime Phe levels and IQ in the early-treated and total tested cases (p < 0.001).Conclusion Early treatment and controlled lifetime phenylalanine levels are the most favorable prognostic factors for neurological outcomes in PKU cases, regardless of baseline phenylalanine levels.