Question
How is phenylketonuria diagnosed?
Answer
Phenylketonuria (PKU) is a treatable genetic metabolic disorder. Early diagnosis and treatment can prevent intellectual impairment and allow the child to lead a normal life. Diagnosis is primarily based on the measurement of phenylalanine concentration in the blood. The phenylalanine concentration in the blood of affected children is usually above 20mg/dl. Diagnostic methods include the phenylalanine dehydrogenase test, fluorescence photometry, amino acid chromatography, amino acid analysis, and the phenylalanine tolerance test. Additionally, tests for ferric chloride and 2,4-dinitrophenylhydrazone in urine can also serve as references. After diagnosis, the child must follow a low-phenylalanine diet to prevent brain damage and ensure normal development.