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Isoleanine/Creatinine Ratio, Urine

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

This urine test measures isoleucine relative to creatinine, helping account for differences in urine concentration.

Quick summary

["An abnormal result may suggest changes in isoleucine excretion and should be interpreted with your other lab results."]

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

Key facts at a glance

LOINC
13765-3
Short code
Isoleucine/Creat Ur
Synonyms
Isoleucine/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 the amount of the amino acid isoleucine in urine compared with the amount of creatinine. The ratio helps account for how concentrated or dilute a urine sample is.

Why might I need this test?

It may be used to evaluate how the body handles isoleucine and other amino acids. It can help investigate suspected inherited disorders of amino acid metabolism, particularly when interpreted alongside symptoms and other tests.

How is the test performed?

A urine sample is analyzed to determine the amount of isoleucine and creatinine present. The laboratory then calculates the isoleucine-to-creatinine ratio.

How do I prepare for the test?

Follow the collection instructions provided by the laboratory. Usually, a first-morning or timed urine sample is requested, and fasting is not required unless your clinician specifically says otherwise.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine isoleucine/creatinine ratio

Frequently asked questions

Is this the same as a urine amino acid test?
It measures a specific part of urinary amino acid metabolism by comparing isoleucine with creatinine. A broader urine amino acid profile may also be needed.
Why is creatinine included?
Creatinine is used to account for urine concentration, which varies throughout the day. This makes the ratio more useful than the isoleucine amount alone.
Does an abnormal result confirm a metabolic disorder?
No. An abnormal result usually requires confirmation with clinical information and additional laboratory tests.
  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