Name of the Procedure:

Phenylalanine (PKU) Test, Blood
Technical name: Phenylalanine Blood Test

Summary

The Phenylalanine (PKU) blood test measures the level of phenylalanine in the blood. Phenylalanine is an amino acid found in protein-rich foods. This test is typically used to diagnose and monitor phenylketonuria (PKU), a genetic disorder that affects the body’s ability to process phenylalanine.

Purpose

The PKU blood test aims to:

• Diagnose phenylketonuria (PKU), a metabolic disorder present from birth.
• Monitor phenylalanine levels in individuals diagnosed with PKU to prevent complications such as intellectual disability and neurological problems.

Indications

• Newborn screening: All newborns are screened for PKU as part of routine newborn screening tests.
• Symptoms such as developmental delays, intellectual disabilities, and eczema which may indicate PKU.
• Family history of PKU or a sibling diagnosed with PKU.

Preparation

• Generally, no specific preparation is needed for the test.
• Inform the healthcare provider of any medications or supplements the patient is taking.
• Fasting is not typically required.

Procedure Description

1. A healthcare professional will clean the puncture site with an antiseptic.
2. Using a sterile needle, a small sample of blood is drawn from a vein, usually from the arm.
3. In newborns, blood is often collected through a heel prick.
4. The blood sample is stored in a special container and sent to a laboratory for analysis.

Duration

The blood collection process typically takes around 5-10 minutes.

Setting

The procedure is performed in a hospital, outpatient clinic, or laboratory.

Personnel

• Phlebotomist or nurse for drawing blood.
• Laboratory technician to analyze the blood sample.
• Doctor to interpret the results and discuss them with the patient or caregiver.

Risks and Complications

• Minor pain or discomfort at the puncture site.
• Possible bruising or bleeding.
• Rarely, infection at the puncture site.

Benefits

• Early detection of PKU in newborns allows for immediate dietary interventions.
• Helps to prevent serious complications such as intellectual disabilities and neurological issues with proper management.
• Effective monitoring of phenylalanine levels in diagnosed individuals to maintain appropriate treatment.

Recovery

• No significant recovery time is needed.
• The puncture site may be sore or bruised for a short time.
• Follow any care instructions provided for the puncture site.

Alternatives

• Urine test for phenylalanine (not commonly used due to less reliability compared to the blood test).
• Genetic testing may also be conducted to confirm PKU.

Patient Experience

• The patient may feel a small pinch or sting when the needle is inserted.
• For newborns, a quick prick on the heel may cause brief crying.
• Minimal discomfort following the procedure.
• Pain management is usually not necessary. Comfort measures, such as holding or soothing an infant, may be helpful.