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Serum or plasma citrulline concentration

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

This test measures the amount of citrulline, an amino acid involved in the urea cycle, which helps remove waste products from your blood. Citrulline is often studied in conditions affecting liver function or nitrogen metabolism.

Quick summary

["Citrulline helps assess how well your body processes waste and supports liver health."]

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

Key facts at a glance

LOINC
26745-0
Short code
Citrulline Amn-sCnc
Synonyms
Citrulline Amn-sCnc
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 Is This Test Done?

Your doctor may order this test if you have symptoms like fatigue, confusion, or swelling that could indicate liver disease, kidney problems, or metabolic disorders. It may also be used to monitor treatment for conditions like urea cycle disorders or liver failure.

What to Expect Before the Test

No special preparation is needed unless instructed. You may provide blood drawn from a vein in your arm or plasma from a tube. If you’re taking medications, let your lab know to avoid potential interference.

What the Results Mean

Results are compared to a general reference range, but exact values can vary by lab. High levels might suggest liver or kidney issues, while low levels could indicate metabolic disorders or urea cycle deficiencies. Your doctor will interpret results in context of your health.

Common Conditions Monitored

This test is often used to evaluate liver function, urea cycle disorders (e.g., citrullinemia), or metabolic imbalances. It may also help diagnose or track conditions like hepatic encephalopathy or certain genetic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Citrulline Level

Frequently asked questions

What causes abnormal citrulline levels?
Abnormal results can stem from liver disease, kidney dysfunction, or metabolic disorders like urea cycle defects. Dietary factors (e.g., high protein intake) or medications may also influence levels, so discuss any changes with your healthcare provider.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will contact you once they’re ready for review.
Can diet affect this test?
Yes, protein-rich foods or certain medications may temporarily alter citrulline levels. Follow your doctor’s instructions on fasting or dietary restrictions if applicable.
  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