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Urinary Ornithine-to-Creatinine Ratio, Random Urine

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

Measures ornithine relative to creatinine in a urine sample to assess urinary ornithine excretion while reducing the effect of urine dilution.

Quick summary

["This urine test evaluates how much ornithine is being excreted and may help assess certain inherited disorders of amino acid metabolism."]

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

Key facts at a glance

LOINC
30049-1
Short code
Ornithine/Creat Ur-Rto
Synonyms
Ornithine/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 ornithine in urine compared with the amount of creatinine. Creatinine is used as a reference marker because its level in urine varies with urine concentration.

Why might I need this test?

The test may be used to evaluate or monitor conditions involving abnormal ornithine metabolism, including hyperornithinemia-hyperammonemia-homocitrullinuria syndrome and certain other inherited metabolic or urea-cycle disorders.

How is the test performed?

A random urine specimen is collected and analyzed in the laboratory. The laboratory measures ornithine and creatinine and calculates the ornithine-to-creatinine ratio.

How do I prepare for the test?

Fasting is usually not required. Follow the collection instructions provided by your healthcare professional, and be sure to record the collection time because this is commonly a random urine test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An elevated ratio may indicate increased urinary excretion of ornithine, which can occur in hyperornithinemia and some other inherited metabolic disorders. Results should be interpreted with blood amino acid testing, ammonia levels, urine organic acids, and other clinical findings. A low or unexpectedly low result may reflect dilute urine, low ornithine intake, medication effects, or reduced creatinine excretion.

Short name

Urine Ornithine-to-Creatinine Ratio

Frequently asked questions

Do I need to fast before this test?
Fasting is generally not required, but follow any specific instructions from your healthcare professional or the laboratory.
What does an elevated urine ornithine-to-creatinine ratio mean?
It may indicate that more ornithine is being excreted than expected. This can occur with inherited disorders of ornithine metabolism and must be interpreted alongside other laboratory results.
Can this urine test diagnose a metabolic disorder by itself?
No. An abnormal result usually requires confirmation and correlation with blood tests, additional urine studies, genetic testing, and clinical findings.
  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