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Phenylglycoluric acid (24-hour urine)

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

This test measures the amount of phenylglycoluric acid in your urine over a 24-hour period. It helps assess how well your body metabolizes phenylalanine, a building block of proteins.

Quick summary

["This test may help diagnose or monitor conditions affecting phenylalanine metabolism."]

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

Key facts at a glance

LOINC
50138-7
Short code
3Me4OH-phenylglycol/Creat Ur-sRto
Synonyms
3Me4OH-phenylglycol/Creat Ur-sRto
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 a 24-hour phenylglycoluric acid test if they suspect a metabolic disorder, such as phenylketonuria (PKU), a genetic condition that prevents the body from breaking down phenylalanine properly. It can also be used to monitor treatment progress or diagnose conditions like tyrosinemia or other inborn errors of metabolism.

How the Test Works

You’ll collect all urine produced in a 24-hour period in a special container. The test measures the total amount of phenylglycoluric acid excreted in this urine sample, which reflects how efficiently your body metabolizes phenylalanine.

Sample Collection Process

To prepare, you’ll typically start collecting urine immediately after waking up. Empty your bladder first, then collect every drop for the full 24 hours. Store the sample in a cool place until you return it to the lab. Your doctor or lab technician will provide detailed instructions.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid certain medications or foods that could interfere with results. Always follow your healthcare provider’s specific instructions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated levels of phenylglycoluric acid in urine can indicate conditions like phenylketonuria, where phenylalanine builds up in the body. Low levels may suggest other metabolic issues or improper sample collection. This test is critical for early diagnosis and management of inherited metabolic disorders.

Short name

24-Hour Phenylglycoluric Acid

Frequently asked questions

What does a high or low result mean?
A high result may signal an inherited metabolic disorder, such as phenylketonuria, where the body cannot properly break down phenylalanine. It could also indicate other conditions affecting amino acid metabolism. Your doctor will review your results in the context of your symptoms and medical history to determine the next steps.
How often should I get this test?
The frequency depends on your medical condition and treatment plan. If you have a known metabolic disorder, your doctor may recommend regular monitoring. If this test is part of routine screening, follow their guidance on how often to repeat it.
Can diet or medications affect this test?
Yes, certain foods, medications, or supplements may influence phenylglycoluric acid levels. For example, high-protein diets or medications that alter amino acid metabolism could impact results. Always inform your doctor about all medications, supplements, or dietary changes before testing.
  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