Introduction to common diagnostic methods for phenylketonuria

Do you know the common diagnostic methods for phenylketonuria? Many people don't know much about phenylketonuria, but if this disease is not treated as soon as possible, it will have serious consequences. However, diagnosis must be made before treatment. Let's take a look at the common diagnostic methods for phenylketonuria!

1. Diagnosis

The diagnosis of phenylketonuria in patients is based on the symptoms of mental retardation, yellow hair, white skin, motor and language development retardation, and elevated phenylalanine in blood tests. It can be diagnosed by excluding other diseases that cause elevated phenylalanine. However, in some places, doctors do not know enough about this disease. When encountering such patients, they fail to think of this disease and do not conduct relevant examinations, which often leads to missed diagnosis or misdiagnosis. Therefore, this disease needs to be taken seriously by doctors. The current newborn disease screening can diagnose PKU before the onset of the disease and provide early treatment, so PKU children are less common than before.

2. Classification of phenylketonuria

Diagnosing phenylketonuria is only a partial diagnosis. Due to the pathogenesis of this disease, there are different types of phenylketonuria, and different types have different treatment methods. Therefore, once PKU is diagnosed, early typing is required. First, urine pterin analysis and red blood cell dihydropterin reductase activity determination are used to divide tetrahydropterin metabolism into two categories: normal and abnormal.

There are 4 types of PKU with normal tetrahydropterin metabolism:

(1) Classic PKU: Phenylalanine concentration ≥1200mmol/L, ineffective to tetrahydrobiopterin treatment.

(2) Moderate hyperphenylalaninemia: blood phenylalanine concentration 360mmol/L～1200mmol/L.

(3) Mild hyperphenylalaninemia: blood phenylalanine concentration is between 120mmol/L and 360mmol/L.

(4) Tetrahydrobiopterin-responsive phenylketonuria: Phenylketonuria that is responsive to tetrahydrobiopterin treatment.