Skip to content

Ammonia, Serum or Plasma (Concentration)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of ammonia, a waste product, in your blood. Ammonia is produced when proteins break down in your body and can build up if your liver isn’t working properly.

Quick summary

["Ammonia levels help check liver function and detect conditions like liver disease or metabolic disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
102402-5
Short code
Ltx Glv Ext Ammon IgE RAST
Synonyms
Ltx Glv Ext Ammon IgE RAST
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rast
CPT
84484
SNOMED
302774002
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 problems. It’s also used to monitor liver function in people with known liver disease or those undergoing treatments that affect liver function.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a liver function panel. Avoid alcohol and certain medications that can affect liver function.

What the Test Involves

A blood sample is drawn from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and shouldn’t cause significant discomfort.

How Results Are Interpreted

Results are compared to a reference range, but exact values can vary by lab. High ammonia levels may indicate liver disease or other metabolic issues, while low levels might suggest dehydration or kidney problems.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum/plasma ammonia level

Frequently asked questions

What does a high ammonia level mean?
High ammonia levels often signal liver problems, such as cirrhosis or hepatitis, where the liver can’t process ammonia properly. It can also occur in metabolic disorders or kidney failure. Your doctor will consider your symptoms and other test results to diagnose the cause.
What does a low ammonia level mean?
Low ammonia levels are less common but may suggest dehydration, kidney issues, or certain medications that affect ammonia metabolism. If your doctor finds it low, they may check for other conditions like liver disease or metabolic disorders.
How often should this test be done?
The frequency depends on your health. If you have liver disease, your doctor may order this test regularly to monitor your condition and adjust treatments as needed. For routine check-ups or unexplained symptoms, it’s usually done once or twice a year.
  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 17, 2026. · Read our editorial policy