Skip to content

Genetic mutation analysis for *pah* (Phenylalanine hydroxylase) in whole blood

Published: August 9, 2026Updated: August 16, 2026

This test checks for genetic changes in the enzyme that helps break down phenylalanine, a natural amino acid. These mutations can be linked to conditions like phenylketonuria (PKU).

Quick summary

["Early detection of phenylalanine hydroxylase gene mutations may help manage metabolic disorders before symptoms develop."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
49014-4
Short code
PAH gene Mut Anl Bld/T
Synonyms
PAH gene Mut Anl Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you or your child have a family history of phenylketonuria (PKU) or other metabolic disorders. It could also be part of a newborn screening program or if you’re considering genetic counseling for a potential pregnancy.

What to Expect Before the Test

You’ll likely provide a small sample of whole blood, often taken from your heel (for infants) or a vein (for adults). The process is quick and usually painless. No special preparation is needed, but check with your provider if you’re on certain medications.

What the Results Mean

Results may identify mutations in the phenylalanine hydroxylase gene. If found, your doctor will work with you to develop a personalized plan, which may include dietary adjustments or monitoring to prevent complications.

Common Conditions Linked to This Test

Positive results could indicate an increased risk of PKU or other phenylalanine-related metabolic disorders. These conditions require lifelong management to avoid developmental delays or health issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: This test is critical for early intervention in phenylketonuria and related disorders. Detecting mutations allows for timely dietary or medical management to prevent long-term harm, particularly in infants and children.

Short name

Phenylalanine hydroxylase gene mutation screening (blood)

Frequently asked questions

Will I need to fast before this test?
No fasting is required for this blood test. However, if you’re pregnant or have a history of metabolic conditions, your provider may give specific instructions.
What does a positive result mean for my health?
A positive result means your body may struggle to break down phenylalanine properly. Your doctor will guide you on next steps, which could include dietary restrictions, enzyme therapy, or monitoring to prevent complications.
Can this test detect all types of phenylalanine hydroxylase mutations?
This test screens for specific mutations in the phenylalanine hydroxylase gene. While it covers many common variants, some mutations may not be detected by this method alone. Your provider may recommend additional testing if needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy