Up until 1970, clinicians believed that dietary treatment was only necessary until the end of childhood. It was thought that the brain was only vulnerable to the toxic effects of elevated Phenylalanine (Phe) blood levels during the period of accelerated development. However with research came concerns about the safety of abandoning the diet at all ages.
Blood Phenylalanine (Phe) levels, which are a marker of the severity of the disorder, are usually stable by the age of five years. There are different classifications of Phenylketonuria (PKU). Generally:
- Patients with blood Phe levels of between 360–1200 μmol/L (6–20 mg/dL) are classified as having mild to moderate PKU.
- Those with blood Phe levels >1200 μmol/L (>20 mg/dL) are classified as having classic PKU.
There are no international guidelines as to what constitutes a safe level of Phe in the blood. However PKU specialists do agree that low Phe blood levels must be maintained throughout life.
Ask your PKU specialist what represents a ‘safe’ blood Phe control target for your child.