24-Hour Urine Phenylpyruvate-to-Creatinine Ratio
A 24-hour urine test that measures phenylpyruvate relative to creatinine. It is sometimes used to monitor phenylalanine metabolism and dietary treatment in people with phenylketonuria.
["This test measures a phenylalanine-related metabolite in urine and may help monitor phenylketonuria treatment."]
Key facts at a glance
- LOINC
- 50361-5
- Short code
- Phenylpyruvate/Creat 24h Ur-sRto
- Synonyms
- Phenylpyruvate/Creat 24h Ur-sRto
- Category
- kidney
- 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
What is this test?
This test measures phenylpyruvate, a metabolite formed from phenylalanine, in urine collected over 24 hours. The result is compared with the amount of creatinine in the same urine sample.
Why might I need this test?
It may be ordered to assess phenylalanine metabolism or to monitor the effectiveness of dietary treatment in someone with phenylketonuria. Creatinine helps account for differences in urine concentration and daily urine output.
How is the test performed?
All urine produced during a full 24-hour period is collected in a labeled container and sent to the laboratory. The laboratory measures phenylpyruvate and creatinine and calculates their ratio.
How do I prepare for the test?
Follow the collection instructions provided by the laboratory or your clinician, including the exact start and stop times. Unless instructed otherwise, continue your prescribed diet and normal fluid intake; fasting is generally not required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated phenylpyruvate-to-creatinine ratio may indicate increased phenylalanine exposure or reduced phenylalanine metabolism, such as inadequate control of phenylketonuria. Results can also be affected by diet, illness, kidney function, and incomplete urine collection, so they should be interpreted alongside blood tests and clinical findings.
Short name
Urine Phenylpyruvate Ratio
Frequently asked questions
Does this test diagnose phenylketonuria?
Why is the result reported as a ratio to creatinine?
What if part of the 24-hour urine collection is missed?
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