Phenylalanine, 30-Day Breast Milk Specimen
Measures phenylalanine in breast milk collected at about 30 days, usually to assess maternal metabolic control when phenylketonuria is a concern.
["This test checks how much phenylalanine is present in a 30-day breast milk specimen."]
Key facts at a glance
- LOINC
- 61449-5
- Short code
- Milk in 30D PhenX
- Synonyms
- Milk in 30D PhenX
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- phenx
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test measures the amount of phenylalanine, an amino acid, in breast milk collected at approximately 30 days after delivery. It may be used when a mother has phenylketonuria or another condition that can affect phenylalanine metabolism.
Why might I need this test?
High phenylalanine levels in a person with phenylketonuria can affect health and may expose a nursing infant to unusually high amounts. The breast milk measurement can help the care team evaluate maternal dietary and medication management.
How is the test performed?
Breast milk is collected at the time specified by the healthcare provider and sent to a laboratory for phenylalanine measurement. The laboratory reports the result for interpretation along with the individual's overall health and other phenylalanine tests.
How do I prepare for the test?
Follow the collection time, container, storage, and delivery instructions provided by the laboratory. Do not make major dietary or medication changes solely to influence this test unless directed by the metabolic care team.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated result may indicate that phenylalanine metabolism or dietary control is not optimal, particularly in someone with phenylketonuria. This can be important because the infant may receive phenylalanine through breast milk. A lower-than-expected result is less common and should be interpreted by the healthcare professional using the laboratory's method and the clinical context.
Short name
Breast Milk Phenylalanine
Frequently asked questions
Is this the same as a newborn phenylalanine screening test?
Why is breast milk tested at 30 days?
Does an abnormal result mean the baby has phenylketonuria?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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