Urine Phenylacetate-to-Creatinine Ratio
Measures urine phenylacetate relative to creatinine. It may help evaluate phenylalanine metabolism, including monitoring of phenylketonuria.
["This test measures a phenylalanine breakdown product in urine and may help assess or monitor phenylketonuria."]
Key facts at a glance
- LOINC
- 13791-9
- Short code
- Phenylacetate/Creat Ur
- Synonyms
- Phenylacetate/Creat 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 phenylacetate, a breakdown product of phenylalanine, in urine. The result is compared with the urine creatinine level to reduce the effect of differences in urine concentration.
Why might I need this test?
The test may be used in the evaluation or dietary monitoring of phenylketonuria, an inherited condition in which the body cannot process phenylalanine normally. It may also be ordered when a clinician is investigating other signs of abnormal phenylalanine metabolism.
How is the test performed?
A urine sample is collected and analyzed in a laboratory. The laboratory reports the amount of phenylacetate relative to the amount of creatinine in the same sample.
How do I prepare for the test?
Follow any instructions provided by your healthcare professional, especially if you have been given a prescribed phenylalanine-restricted diet. Tell the clinician about your diet, medicines, supplements, and any kidney problems because these can affect interpretation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An increased urine phenylacetate-to-creatinine ratio may indicate increased phenylalanine breakdown and can occur in untreated or inadequately controlled phenylketonuria. Results can also be affected by dietary phenylalanine intake, urine concentration, kidney function, and other metabolic conditions, so the ratio should be interpreted with other clinical and laboratory findings.
Short name
Urine Phenylacetate/Creatinine Ratio
Frequently asked questions
Is this the same as a blood phenylalanine test?
Why is creatinine included in the result?
Can diet and medicines affect 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