What Are the Symptoms of Phenylketonuria (PKU) in Newborns?
May 17, 2022
Source: Cainiu Health
Dr. Xie Zixing
Introduction
In newborns with phenylketonuria (PKU), neurological abnormalities appear early, such as hyperexcitability, hyperactivity, mild hypertonia, hyperreflexia, and seizures; these symptoms typically diminish significantly after a period of time. Subsequently, hypotonia, lethargy, and convulsions commonly develop. If left untreated, mortality during childhood is high. Additionally, newborns with PKU often exhibit characteristic physical features due to impaired melanin synthesis.
In daily life, physical discomfort occasionally occurs. When such discomfort arises, it’s important not to panic. So, what are the symptoms of phenylketonuria (PKU) in newborns?
What Are the Symptoms of Phenylketonuria in Newborns?
Newborns with phenylketonuria often exhibit early neurological abnormalities, such as excessive excitability, hyperactivity, mild hypertonia, hyperreflexia, or seizures—symptoms that typically diminish over time. Later, they commonly develop hypotonia, lethargy, and convulsions. Without timely treatment, mortality during childhood is relatively high. Due to insufficient melanin synthesis, affected infants gradually experience lightening of hair and skin color several months after birth. Their skin may become dry, and some children with phenylketonuria—particularly those exhibiting features of ketoacidosis—may frequently develop eczema.
If phenylketonuria is diagnosed in a newborn, prompt treatment is essential to avoid missing the optimal therapeutic window, which could otherwise lead to irreversible brain damage. The primary underlying cause of this condition is a genetic mutation resulting in deficiency of a specific enzyme—phenylalanine hydroxylase—leading to impaired metabolism of phenylalanine. Consequently, phenylalanine and its toxic metabolites accumulate in the body, triggering a cascade of adverse effects, including intellectual disability.
Additionally, phenylketonuria may present with other clinical manifestations. Therefore, individuals experiencing any physical discomfort should seek medical evaluation promptly to determine the underlying cause and receive appropriate management. We hope this information has been helpful. Wishing you good health and a joyful life!
