Patient's question:
My friend's baby is two years old this year. Due to a cold and fever, they went to a nearby hospital for a thorough examination, where it was diagnosed as phenylketonuria. The baby had a high fever, persistent cough, and cold hands and feet. After a period of treatment, when they went for a follow-up examination, the doctor said it was already normal. What is the normal value for phenylketonuria after a follow-up examination?Doctor's answer:
A slight decrease in phenylalanine concentration in the blood indicates the need to test for phenylalanine levels to diagnose phenylketonuria. Screening for this condition is typically performed shortly after a child is born, making it a mandatory method. Generally, if the blood phenylalanine level is below 120 mmol/L, it is considered positive, and further diagnosis is required. If blood tyrosine concentration can also be tested, it is beneficial as it allows for the estimation of the phenylalanine to tyrosine ratio. A ratio below 2 suggests a positive result.