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Arginine:Urea Ratio (AUR) in Serum

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

This test measures the ratio of arginine to urea in your blood, which can help assess how well your kidneys are processing certain proteins and waste products.

Quick summary

["Understanding kidney function through protein breakdown and waste clearance."]

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

Key facts at a glance

LOINC
35951-3
Short code
MRA Ao arch
Synonyms
MRA Ao arch
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mr-angio
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

The test evaluates the balance between arginine—a key amino acid—and urea—a waste product formed when proteins are broken down. This ratio can reflect how efficiently your kidneys filter and process these substances.

Why It Matters in Kidney Health

High arginine levels relative to urea may indicate impaired kidney function or conditions affecting protein metabolism, such as certain liver or kidney diseases.

How It’s Performed

A blood sample is drawn, and the ratio of arginine to urea is measured using a specialized laboratory method. Results are typically reported as a ratio value.

Common Uses

This test may be used in cases where doctors suspect kidney disease, liver dysfunction, or metabolic disorders that alter protein breakdown.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Arginine-to-Urea Ratio

Frequently asked questions

Why might my doctor order this test?
Your doctor may recommend this test if they suspect kidney disease, liver problems, or other conditions that affect how your body processes proteins and waste products.
What do the results mean?
Results show the ratio of arginine to urea. Abnormal ratios may signal kidney or metabolic issues, but interpretation depends on clinical context and other test results.
Is this test painful or uncomfortable?
A blood draw is generally mild discomfort but brief. Most people find it quick and manageable, similar to other routine blood 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