Question
Our baby vomits every day, has small red rashes on their face, and cries a lot. After going to the hospital for blood tests, the doctor said the child might have Phenylketonuria. How can it be diagnosed?
Answer
Phenylketonuria is a congenital metabolic disorder caused by a deficiency in the liver enzyme phenylalanine hydroxylase (PAH), leading to impaired metabolism of phenylalanine (PA) and subsequently damaging the central nervous system. The diagnosis of affected infants primarily relies on measuring the concentration of phenylalanine in the blood. When the concentration of phenylalanine in the infant’s blood exceeds 20 mg/dl, and symptoms such as intellectual disability, yellow hair, pale skin, delayed motor and language development are present, Phenylketonuria can be diagnosed by excluding other diseases that may cause an increase in phenylalanine levels. Newborns should be screened for the disease early to ensure timely diagnosis of Phenylketonuria before symptoms appear.