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Isoleucine/Creatinine Ratio, Urine

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

A urine test that measures isoleucine relative to creatinine, which can help evaluate amino acid handling and identify possible metabolic disorders.

Quick summary

["This ratio can help detect abnormal isoleucine excretion, but results must be interpreted with symptoms and other laboratory findings."]

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

Key facts at a glance

LOINC
30052-5
Short code
Isoleucine/Creat Ur-Rto
Synonyms
Isoleucine/Creat Ur-Rto
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 isoleucine in urine compared with the amount of creatinine. Isoleucine is an essential building block, or amino acid, that the body normally breaks down and uses.

Why might I need this test?

A clinician may order this test when unexplained symptoms suggest an inherited problem with amino acid metabolism. It may also be used to monitor people with known metabolic conditions.

How is the test performed?

A urine sample is collected and analyzed in a laboratory to determine the isoleucine-to-creatinine ratio. Creatinine is used as a comparison marker to help account for differences in urine concentration.

How do I prepare for the test?

Follow the laboratory's urine-collection instructions and tell the clinician about medicines, supplements, diet changes, or recent illness. Unless specifically requested, follow your usual routine; fasting is not generally required.

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 is a specific part of urine amino acid testing that expresses isoleucine relative to creatinine. A broader urine amino acid profile may also be ordered.
Does an abnormal result mean I have an inherited disease?
Not necessarily. Abnormal results can be influenced by diet, illness, medicines, and other factors, so a clinician must interpret them in your clinical context.
Do I need to collect a 24-hour urine sample?
This test is commonly performed on a urine sample rather than a 24-hour collection. Confirm the collection method with the laboratory or ordering 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