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Phenyl Lactate/Creatinine [Mass Ratio] in Urine

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

A urine test measuring phenyl lactate relative to creatinine. It may help evaluate phenylalanine metabolism, including suspected phenylketonuria, alongside other results.

Quick summary

["This test helps assess phenylalanine metabolism by measuring urinary phenyl lactate in relation to creatinine."]

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

Key facts at a glance

LOINC
108495-3
Short code
Phenyllactate/Creat Msmt Ur
Synonyms
Phenyllactate/Creat Msmt Ur
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Critical range
— – 4 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 urine test measures phenyl lactate, a substance produced during phenylalanine metabolism, and compares its amount with the amount of creatinine in the same sample.

Why might I need this test?

The test may be used when a metabolic condition involving phenylalanine, such as phenylketonuria, is suspected or being monitored. It is usually interpreted with blood tests and other clinical information.

How is the test performed?

A urine sample is collected and analyzed in the laboratory. Creatinine is used as a reference because urine concentration can vary, helping the laboratory compare phenyl lactate with the amount of creatinine in the sample.

How do I prepare for the test?

Follow the laboratory's instructions for urine collection, including whether a single sample or a timed collection is required. Do not make major dietary changes unless your healthcare professional advises you to do so.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An increased amount of phenyl lactate in urine may occur when phenylalanine metabolism is impaired, including in phenylketonuria. Urine levels can also be affected by diet, collection timing, and hydration, so an abnormal result should be interpreted with other laboratory findings and clinical assessment.

Short name

Urine phenyl lactate-to-creatinine ratio

Frequently asked questions

What does the creatinine adjustment mean?
Creatinine is used to account for differences in urine concentration. The ratio provides a more comparable measure of urinary phenyl lactate than an unadjusted result alone.
Does an abnormal result diagnose phenylketonuria?
No. This result may support further evaluation, but it cannot diagnose phenylketonuria by itself. Blood phenylalanine testing and clinical assessment are also important.
Can diet affect the result?
Yes. Phenylalanine intake and other dietary factors may influence the amount of phenyl lactate in urine. Keep your diet consistent and follow any instructions provided by your clinician.
  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