Phenylacetate/Creatinine Ratio, Urine — Turbidimetric Measurement
This urine test measures phenylacetate relative to creatinine and can help assess phenylalanine metabolism, particularly in people with phenylketonuria.
["The ratio helps evaluate how the body is breaking down phenylalanine, especially when monitoring phenylketonuria."]
Key facts at a glance
- LOINC
- 108508-3
- Short code
- Phenylacetate/Creat Msmt Ur
- Synonyms
- Phenylacetate/Creat Msmt Ur
- 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 the amount of phenylacetate in urine relative to the amount of creatinine. Creatinine is used to account for differences in urine concentration, making the result more useful for comparison.
Why might I need this test?
Phenylacetate is a product formed when the body breaks down phenylalanine. This test may be used to monitor people with phenylketonuria, or PKU, and assess how well their treatment is controlling phenylalanine metabolism.
How is the test performed?
A urine sample is collected and analyzed in the laboratory. The laboratory measures phenylacetate and creatinine and reports their relationship as a ratio; the analytical method used for each component may vary by laboratory.
How do I prepare for the test?
Follow the laboratory's urine-collection instructions, including whether a first-morning, timed, or spot collection is required. Fasting is generally not necessary unless your care team specifically requests it.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A higher ratio may indicate increased urinary phenylacetate, which can occur when phenylalanine metabolism is not well controlled. A lower ratio may reflect changes in urine concentration, metabolism, medication, diet, or laboratory measurement. Your clinician should interpret the result alongside your overall PKU treatment and other phenylalanine measurements.
Short name
Urinary phenylacetate-to-creatinine ratio
Frequently asked questions
Is this the same as a blood phenylalanine test?
Why is creatinine included in the result?
Does an abnormal result mean my treatment is not working?
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