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Urine Homocitrulline-to-Creatinine Ratio

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

Measures urine homocitrulline relative to creatinine, helping evaluate an amino-acid disorder that can affect the brain, nerves, and liver.

Quick summary

["This urine test can help identify or monitor conditions that cause elevated homocitrulline levels."]

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

Key facts at a glance

LOINC
32248-7
Short code
Homocitrulline/Creat Ur-Rto
Synonyms
Homocitrulline/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?

Homocitrulline is an amino acid produced during metabolism. This test measures the amount of homocitrulline in urine relative to creatinine, a substance used to account for urine concentration.

Why might I need this test?

The test may be used to evaluate symptoms or family history suggesting an inherited metabolic disorder, especially hyperhomocitrullinemia-hyperornithinemia-hyperammonemia syndrome. It may also help monitor treatment or recurrence of a related condition.

How is the test performed?

A urine sample is collected and analyzed in a laboratory. The laboratory measures homocitrulline and creatinine and calculates their ratio.

How do I prepare for the test?

Follow your clinician's instructions for collecting and timing the urine sample. Tell the laboratory if you are taking medicines or supplements, because some treatments and vitamin preparations may affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An elevated homocitrulline-to-creatinine ratio may occur with inherited disorders of amino-acid metabolism, including HHH syndrome. Results must be interpreted alongside symptoms, kidney function, other amino-acid measurements, and sometimes genetic testing, because a single abnormal result does not establish a diagnosis.

Short name

Urine homocitrulline/creatinine ratio

Frequently asked questions

What does the ratio show?
It compares urinary homocitrulline with urinary creatinine. Creatinine helps adjust for variations in how concentrated or dilute the urine sample is.
Does an abnormal result mean I have a genetic disorder?
Not by itself. An elevated result can suggest a metabolic condition, but additional laboratory findings, clinical evaluation, and sometimes genetic testing are needed to confirm the cause.
Is this the same as a homocysteine test?
No. Homocitrulline and homocysteine are related but different substances, and they are measured in different ways to evaluate different metabolic pathways.
  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