Final answer:
It is mandatory to test for PKU at birth in the United States and Canada. Immediate screening is vital to begin treatment and dietary adjustments to mitigate the damaging effects of PKU on the nervous system and brain development. Management includes a low phenylalanine diet and avoiding aspartame.
Step-by-step explanation:
Phenylketonuria (PKU) is a genetic disorder that is screened for shortly after birth. For infants born in the United States and Canada, it is mandatory to test for PKU at birth. The screening is crucial as PKU phenylalanine hydroxylase enzyme deficiency leads to the inability to convert phenylalanine to tyrosine, causing toxic levels of phenylalanine that can severely damage the central nervous system and brain. Symptoms caused by PKU, such as hyperactivity, intellectual disability, and seizures, can be mitigated with an early start on a modified diet low in phenylalanine.
For pregnant individuals with PKU, there is a high risk of excess phenylalanine crossing the placenta and affecting fetal development, potentially resulting in heart defects and intellectual disability. Avoidance of artificial sweeteners like aspartame, which are high in phenylalanine, is especially important for people with PKU, along with careful monitoring of certain animal products and starches. The drug Kuvan has been approved since 2007 for those with lower activities of phenylalanine hydroxylase, as it aids in reducing blood phenylalanine levels.
The test for PKU can be done by adding a 10% FeCl3 solution to the patient's fresh urine, observing an emerald green color that fades after 20 minutes. This test, along with genetic screening, confirms the diagnosis of PKU.