Phenylketonuria (PKU) Screening

Phenylketonuria (PKU) is a genetic disorder characterized by the inability of the body to break down an amino acid called phenylalanine (Phe). PKU screening is a test used to detect this condition in newborns.

Purpose of PKU Screening

The primary purpose of PKU screening is to identify infants with PKU early, so that treatment can be initiated promptly to prevent intellectual disability and other complications associated with the disorder.

How PKU Screening is Performed

PKU screening is typically performed using a blood test, which involves pricking the heel of the newborn to collect a few drops of blood. The blood sample is then sent to a laboratory for analysis.

Types of Tests Used for PKU Screening

There are two main types of tests used for PKU screening:

• Guthrie test: This is a bacterial inhibition assay that measures the level of phenylalanine in the blood.
• Tandem mass spectrometry (MS/MS): This is a more sensitive and specific test that can detect multiple amino acid disorders, including PKU.

Interpretation of Results

The results of the PKU screening test are usually reported as follows:

• Normal: The level of phenylalanine in the blood is within the normal range, and no further testing is needed.
• Abnormal: The level of phenylalanine in the blood is elevated, and further testing is required to confirm the diagnosis.

Follow-up Testing

If the initial screening test is abnormal, follow-up testing may include:

• Repeat blood test: To confirm the results of the initial test.
• Genetic testing: To identify the specific genetic mutation responsible for PKU.
• Clinical evaluation: To assess the infant's overall health and development.

Treatment and Management of PKU

If a diagnosis of PKU is confirmed, treatment typically involves:

• Dietary restriction: Limiting the intake of phenylalanine-containing foods and supplements.
• Specialized formula: Using a formula that is low in phenylalanine.
• Regular monitoring: Regular blood tests to monitor the level of phenylalanine in the blood and adjust treatment as needed.

Importance of Early Detection and Treatment

Early detection and treatment of PKU are crucial to prevent intellectual disability, seizures, and other complications associated with the disorder. With proper management, individuals with PKU can lead healthy and normal lives.

Frequently Asked Questions (FAQs)

What is Phenylketonuria (PKU) screening?
A medical test to detect PKU, a genetic disorder that affects the body's ability to break down phenylalanine.

Why is PKU screening performed?
To identify newborns with PKU, allowing for early treatment and prevention of intellectual disability and other complications.

How is PKU screening typically done?
Through a blood test, usually a heel prick, on newborns, typically within the first few days of life.

What does the blood test measure?
The level of phenylalanine in the blood, which can indicate if the baby has PKU.

What are the possible results of PKU screening?
Either negative, indicating no signs of PKU, or positive, suggesting further testing is needed to confirm diagnosis.

If the screening result is positive, what happens next?
A follow-up test, such as a blood or urine test, is performed to confirm the diagnosis and determine the severity of PKU.

Is PKU screening mandatory for newborns?
In many countries, yes, PKU screening is part of routine newborn screening programs, but requirements may vary by region.

Can PKU be treated if detected early?
Yes, with a strict diet low in phenylalanine and possibly other interventions, individuals with PKU can lead relatively normal lives.

What are the consequences of untreated PKU?
If left untreated, PKU can lead to intellectual disability, seizures, and other serious health problems.

Is PKU screening only for newborns?
No, while newborn screening is standard, older children and adults may also undergo testing if symptoms or family history suggest a risk of PKU.