What Is Phenylketonuria (PKU) in Newborns?
Jun 07, 2022
Source: Cainiu Health
Dr. Xie Zixing
Introduction
Phenylalanine and its other metabolites accumulate in the body, leading to a series of clinical symptoms, including intellectual disability. Newborns with phenylketonuria (PKU) often exhibit fair skin and frequently develop eczema. Reduced melanin synthesis results in light-colored, dry, and lusterless hair. Additional features include microcephaly, delayed eruption of deciduous teeth, and the excretion of sweat and urine with an unpleasant, musty, mouse-like odor.
It is common for some newborns to appear healthy at birth, only to develop abnormal symptoms after a period of time—leading to a diagnosis of neonatal phenylketonuria (PKU). So, what exactly is neonatal PKU?
What Is Neonatal Phenylketonuria?
Neonatal phenylketonuria is a relatively common autosomal recessive genetic disorder. It is primarily caused by gene mutations that result in deficiency of a specific enzyme—phenylalanine hydroxylase—in affected infants. This deficiency impairs the normal metabolism of phenylalanine, causing accumulation of phenylalanine and its metabolites in the body, which subsequently leads to a range of clinical manifestations, most notably intellectual disability. Externally, infants with PKU often exhibit fair skin and frequently develop eczema. Reduced melanin synthesis results in light-colored, dry, and lusterless hair. Additional features may include microcephaly, delayed eruption of primary teeth, and a distinctive musty or “mousy” odor in sweat and urine.
Phenylalanine-restricted dietary therapy remains the most effective treatment for PKU. Once diagnosed, infants should immediately begin a phenylalanine-restricted diet, with strict control over total protein intake—particularly animal-derived proteins. It is essential to ensure adequate caloric intake, sufficient (but carefully regulated) protein, and a precise, prescribed amount of phenylalanine. Supplementation with vitamins and trace elements is also critical. In addition, early rehabilitation interventions should be implemented to support optimal neurodevelopmental outcomes. The earlier dietary management begins, the better the long-term prognosis.
In daily care, pay close attention to your baby’s nutritional balance and ensure adequate rest and quality sleep. We hope this information has been helpful!
