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24-Hour Urinary Phenols (Free) with Dietary Caffeine-Free Collection

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

This test measures certain chemicals, called phenols, that your body naturally produces and excretes in your urine over 24 hours. It helps assess how well your liver and kidneys are processing these substances, especially when caffeine is avoided to avoid interference.

Quick summary

["This test helps evaluate liver and kidney function by tracking free phenols in urine over a full day, excluding caffeine’s influence."]

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

Key facts at a glance

LOINC
61489-1
Short code
Size diet colas caffeine free PhenX
Synonyms
Size diet colas caffeine free PhenX
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenx
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if they suspect issues like liver disease, kidney problems, or metabolic disorders. It can also be part of a broader evaluation for conditions affecting how your body breaks down certain chemicals.

What to Expect Before the Test

You’ll need to collect all urine for 24 hours, starting and ending with your first morning urine. Follow your provider’s instructions carefully to ensure accuracy, including avoiding caffeine during this period.

How the Test Works

After collecting urine, it’s analyzed in a lab to measure free phenol levels. The test uses a specialized method to detect these chemicals without interference from other substances like caffeine.

What the Results Mean

Results help identify abnormal processing of phenols, which may indicate liver or kidney dysfunction. Elevated levels could signal metabolic or organ-related issues that need further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Free Phenols (24h Urine)

Frequently asked questions

What does a high or low result mean?
High levels could mean your liver or kidneys aren’t working as expected to process phenols, which may require further testing or medical review. Low levels might need investigation into diet, metabolism, or other factors.
How long will I need to prepare for this test?
You’ll need to prepare for 24 hours of urine collection, including avoiding caffeine. Your provider will give detailed instructions to ensure accuracy. Follow them closely to avoid delays or errors.
Is this test painful or uncomfortable?
No, this test involves collecting urine over 24 hours—no injections, needles, or discomfort. Focus on following your collection instructions to ensure reliable results.
  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