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Ammonia (serum/plasma concentration)

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

This test measures the amount of ammonia, a waste product, in your blood. High levels may indicate liver or kidney problems.

Quick summary

["Ammonia levels help check liver function and kidney health."]

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

Key facts at a glance

LOINC
98665-3
Short code
SNAP amplitude R sural n
Synonyms
SNAP amplitude R sural n
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nerve-conduction
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

Why This Test Is Done

Your doctor may order this test if you have symptoms like confusion, fatigue, or nausea, or if they suspect liver disease (such as cirrhosis) or kidney problems. It can also be used to monitor treatment for conditions like liver failure or metabolic disorders.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a liver function panel. Bring any medications you’re taking to your appointment.

How the Test Is Performed

A blood sample is drawn from a vein in your arm by a healthcare professional. The blood is sent to a lab for analysis.

What the Results Mean

Results are compared to a reference range, but exact values can vary by lab. High ammonia levels may signal liver dysfunction, metabolic disorders, or kidney issues. Low levels are less common but may occur with certain medications or conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/plasma ammonia level

Frequently asked questions

What causes high ammonia levels?
High ammonia can result from liver disease (e.g., cirrhosis), kidney failure, severe dehydration, or certain medications. It can also appear in metabolic disorders like urea cycle defects.
What causes low ammonia levels?
Low ammonia is rare but may occur with certain medications (e.g., carbamazepine), liver disease in advanced stages, or severe infections.
Can diet affect ammonia levels?
Dietary protein intake may influence ammonia indirectly, but fasting is typically required for accurate results. Avoid excessive protein-rich foods before testing unless instructed by your doctor.
  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