24-Hour Urinary Phenylglycine (or Phenylglycine Metabolite) Excretion
This test measures the amount of certain breakdown products of phenylalanine (an amino acid) in your urine over 24 hours. It helps assess how well your body is processing phenylalanine, which is important in conditions like phenylketonuria (PKU).
["This test helps diagnose or monitor metabolic conditions linked to phenylalanine metabolism."]
Key facts at a glance
- LOINC
- 21043-5
- Short code
- 3Me4OH-phenylglycol 24h Ur-mCnc
- Synonyms
- 3Me4OH-phenylglycol 24h Ur-mCnc
- Category
- glucose
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have symptoms of a metabolic disorder, such as intellectual disability, developmental delays, or behavioral issues. It’s also used in newborn screening programs to detect phenylketonuria (PKU) early. In adults, it may be checked if you have unexplained neurological problems or if you’re taking medications that affect phenylalanine metabolism.
What to Expect Before the Test
You’ll collect all urine for a full 24-hour period in a clean container. Start and end timing at the same time each day (e.g., midnight to midnight). Drink plenty of water to help flush out phenylalanine metabolites. Avoid special diets unless instructed by your doctor.
What Happens During the Test
No special procedure is needed—just submit the 24-hour urine sample to your lab. The lab will analyze the sample for specific phenylglycine metabolites using advanced techniques like chromatography.
What the Results Mean
Results are compared to reference ranges for healthy individuals. High levels may indicate PKU or other phenylalanine-related disorders, while low levels might suggest an underlying metabolic issue or medication effect. Your doctor will interpret results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated levels of phenylglycine metabolites in urine are strongly associated with phenylketonuria (PKU), a genetic disorder where the body cannot properly break down phenylalanine. Early detection and management (through diet or medication) can prevent long-term brain damage. This test is critical for newborn screening programs to identify PKU before symptoms appear. In adults, abnormal results may signal other metabolic disorders or conditions affecting phenylalanine metabolism, prompting further evaluation.
Short name
24h Urine Phenylglycine
Frequently asked questions
How is this test different from a regular urine test?
What if I miss part of the urine collection?
Can I take my usual medications while doing this test?
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