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Kynurenine-to-Creatinine Ratio, Urine

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

A urine test that compares kynurenine with creatinine. It is sometimes used to help evaluate vitamin B6 status and other causes of altered kynurenine metabolism.

Quick summary

["This ratio adjusts urine kynurenine for urine concentration and may help assess vitamin B6 metabolism."]

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

Key facts at a glance

LOINC
53507-0
Short code
Kynurenin/Creat Ur-sRto
Synonyms
Kynurenin/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 kynurenine and creatinine in a urine sample and calculates their ratio. Creatinine is used as a reference to help account for how concentrated or dilute the urine is.

Why might I need this test?

The test may be ordered to help evaluate vitamin B6 status or investigate conditions that affect kynurenine metabolism. Results are interpreted along with symptoms, diet, medications, kidney function, and other laboratory findings.

How is the test performed?

A urine specimen is collected and tested to measure kynurenine and creatinine. The laboratory then divides the kynurenine result by the creatinine result to calculate the ratio.

How do I prepare for the test?

Follow the collection instructions provided by your healthcare professional. Depending on the test order, this may be a single urine sample or urine collected over 24 hours; be sure to include all urine required for the specified collection period.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An elevated urine kynurenine-to-creatinine ratio can occur with vitamin B6 deficiency or impaired vitamin B6 metabolism. Results may also be affected by hydration, kidney function, diet, medications, pregnancy, and other conditions affecting kynurenine metabolism, so an abnormal value does not identify a single cause by itself.

Short name

Urine kynurenine-to-creatinine ratio

Frequently asked questions

Why is creatinine included in this urine test?
Creatinine helps show how concentrated the urine is. Including it makes the kynurenine measurement less dependent on urine dilution.
What does an elevated ratio mean?
An elevated ratio may be associated with vitamin B6 deficiency or impaired vitamin B6 metabolism. Other factors can also affect the result, so your clinician should interpret it with your medical history and other tests.
Do I need to collect all of my urine for 24 hours?
It depends on the instructions for your test order. Some orders use a single urine sample, while others require a timed 24-hour collection.
  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