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Oxypurinol/Creatinine Ratio, Urine

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

Measures urinary oxypurinol relative to urine creatinine to help evaluate exposure to allopurinol, an active metabolite of which is oxypurinol.

Quick summary

["This urine ratio can help your clinician assess allopurinol exposure and whether you are taking the medication consistently."]

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

Key facts at a glance

LOINC
75132-1
Short code
Oxipurinol/Creat Ur-sRto
Synonyms
Oxipurinol/Creat 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 oxypurinol, an active metabolite of the gout medicine allopurinol, in urine. The result is divided by the urine creatinine level to form an oxypurolinol-to-creatinine ratio.

Why might I need this test?

A clinician may use this test to help monitor allopurinol exposure, treatment adherence, or response when managing gout or high uric acid. It may also be useful when medication levels or adherence are uncertain.

How is the test performed?

You provide a urine sample according to your clinician's or laboratory's instructions. The laboratory measures oxypurinol and creatinine in the sample and calculates their ratio; urine creatinine helps account for differences in urine concentration.

How do I prepare for the test?

Follow the collection instructions exactly, including any specified collection time. Tell your clinician about missed doses, recent changes in allopurinol, other medicines, and kidney problems; do not stop prescribed medication without medical advice.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A lower-than-expected ratio may suggest reduced medication exposure, missed doses, or differences in metabolism. A higher ratio may reflect greater exposure, impaired kidney clearance, or urine-concentration effects, so the result must be interpreted alongside the medication history, kidney function, and other clinical findings.

Short name

Urine oxypurinol/creatinine ratio

Frequently asked questions

What does the urine oxypurinol/creatinine ratio show?
It shows the amount of oxypurinol in urine relative to creatinine. This can help estimate exposure to allopurinol and assess whether the medicine is being taken consistently.
Is this the same as a uric acid blood test?
No. This urine test measures oxypurinol, a metabolite of allopurinol, and does not replace a blood uric acid test used to monitor gout or hyperuricemia.
Can I take the test while using allopurinol?
Yes, the test is generally intended to be performed while you are taking the prescribed medicine. Do not change or skip doses without instructions from your clinician, and tell the laboratory when the last dose was taken.
  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