Homocitrulline/Creatinine Ratio, Urine
This urine test measures homocitrulline relative to creatinine. It is mainly used to help evaluate possible disorders of amino acid and urea-cycle metabolism.
["An elevated urine homocitrulline-to-creatinine ratio may indicate an inherited metabolic disorder and should be interpreted with other tests."]
Key facts at a glance
- LOINC
- 79592-2
- Short code
- Homocitrulline/Creat Ur-sRto
- Synonyms
- Homocitrulline/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 homocitrulline, an amino acid-related substance, in urine. Creatinine is measured at the same time so the homocitrulline result can be adjusted for how concentrated the urine is.
Why might I need this test?
The test may be ordered when symptoms suggest an inherited disorder of urea-cycle or amino acid metabolism, particularly hyperhomocitrullinemia, hyperornithinemia, hyperammonemia syndrome. It is also used in the evaluation of unexplained developmental, neurologic, or metabolic problems.
How is the test performed?
A urine specimen is collected and analyzed in the laboratory. The laboratory measures homocitrulline and creatinine and may calculate their ratio to account for variations in urine concentration.
How do I prepare for the test?
No special preparation is usually required, but follow the laboratory's collection instructions. The type and timing of urine collection can matter, so tell the laboratory if you are pregnant, taking medications or supplements, or have a known kidney or urinary condition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated homocitrulline-to-creatinine ratio may occur in inherited urea-cycle disorders, including hyperhomocitrullinemia, hyperornithinemia, hyperammonemia syndrome. Results can also be affected by kidney function, diet, medications, and other metabolic conditions. The result should be interpreted with medical history, genetic testing when appropriate, and additional amino acid, ammonia, and metabolic tests.
Short name
Urine homocitrulline ratio
Frequently asked questions
Is this the same as a blood homocysteine test?
Why is creatinine included in the test?
Does an abnormal result confirm a genetic disorder?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy