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Arginine: Citrulline Ratio (Serum/Plasma)

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

This test measures the ratio of arginine to citrulline in your blood, which helps assess kidney function and metabolic health.

Quick summary

["A ratio that reflects kidney function and nitrogen metabolism."]

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

Key facts at a glance

LOINC
13392-6
Short code
Citrulline Amn-mCnc
Synonyms
Citrulline Amn-mCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms of kidney disease, such as fatigue, swelling, or changes in urine output. It may also be used to monitor kidney function in people with conditions like chronic kidney disease or those taking certain medications that affect kidney function.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves a blood draw, but this is not always required. Bring your medical records or a list of medications to your appointment.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. The blood sample is then sent to a lab for analysis. The test measures the concentration of arginine and citrulline in your serum or plasma.

What the Results Mean

The ratio itself doesn’t have a standard reference range, but it can help identify imbalances linked to kidney dysfunction or metabolic disorders. Your doctor will interpret the results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Arginine-Citrulline Ratio

Frequently asked questions

What causes an abnormal arginine-citrulline ratio?
Abnormal ratios may result from kidney disease, liver problems, certain genetic disorders (like urea cycle defects), or medications that affect metabolism. High levels of citrulline alone may suggest liver issues, while low arginine levels could indicate kidney dysfunction.
How often should this test be repeated?
Your doctor will determine how often to repeat the test based on your condition. If you have chronic kidney disease or another ongoing health issue, follow-up may be scheduled every few months or as needed to monitor changes.
Can diet affect this test result?
Dietary changes may influence arginine and citrulline levels, especially if you consume high-protein foods. If fasting is required, avoid excessive protein intake before the test to ensure accurate results.
  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