Blood
Ammonia
Also known as: NH3, Blood Ammonia
CONVERT & COMPARE
µmol/L
=
25.5
µg/dL
=
15
umol/L
=
15
mcmol/L
=
25.5
mcg/dL
=
25.5
ug/dL
About Ammonia
An ammonia levels test measures the amount of ammonia in a sample of your blood. Ammonia is also called NH3. It is a normal waste product in your body, formed during the breakdown (metabolism) of protein. Healthy bacteria in your intestines make ammonia when you digest protein in the foods you eat.
Normally, your liver changes ammonia into another waste product called urea. Your kidneys get rid of urea in urine (pee). This process is called the urea cycle.
When you're healthy, the urea cycle prevents ammonia from building up in your blood. This is important because ammonia is toxic (poisonous) to the brain. Very high ammonia levels, especially when they rise quickly (such as in newborns with urea cycle disorders, in Reye syndrome, or in sudden severe liver failure), can cause confusion, coma, and even permanent brain damage if not treated. In adults with long-standing liver disease, blood ammonia levels often go up and down without closely matching how a person feels, so the level alone does not predict how serious symptoms will be.
Liver disease is the most common cause of high ammonia levels. Other causes include kidney failure and genetic disorders called urea cycle disorders.
Main source: MedlinePlus ↗
Useful for
Help diagnose conditions that cause high ammonia levels in people who have symptoms. These conditions include hepatic encephalopathy, Reye syndrome, and urea cycle disorders.
Hepatic encephalopathy happens when toxins, including ammonia, build up in your brain because your liver is unable to break them down. It can cause memory loss, confusion, loss of consciousness, and coma.
Reye syndrome is a rare disease that damages the brain and liver. Without treatment, it causes death. It mostly happens in children younger than 15 who have had a viral infection that causes a fever, such as chickenpox or the flu. Taking aspirin during a viral illness may increase the risk of Reye syndrome.
Urea cycle disorders (UCDs) are a group of rare genetic conditions that you inherit from your parents. If you have a UCD, you lack enzymes that help change ammonia into urea. An enzyme is a protein that speeds up certain chemical reactions in your body. Symptoms may show up shortly after birth or later in life.
Help look into possible liver damage from medicines or from severe hepatitis or cirrhosis (scarring of the liver).
Monitor conditions that cause high ammonia levels and check if treatment is working.
Main source: MedlinePlus ↗
Interpretation
Your provider will use your test results, symptoms, and medical history to understand what your ammonia levels say about your health. Normal levels vary with age, but in general, low levels are normal and healthy.
If your test results are normal, your provider will order other tests to find out what's causing your symptoms.
If your test results show ammonia levels that are higher than normal, it usually means that your body is having trouble getting rid of ammonia. Many types of health conditions can cause high ammonia levels, including severe liver problems such as hepatic encephalopathy, cirrhosis, severe hepatitis, Reye's syndrome, and liver injury from medicines. Heart failure, advanced kidney problems, and severe lung disease such as emphysema can also raise ammonia. The level of ammonia in your blood doesn't always match how severe brain symptoms from liver disease are.
If the results of an ammonia levels test are high, more tests will usually be done to diagnose the cause. Treatment will depend on the condition that's causing the problem. If you have questions about your test results or treatment, talk with your provider.
For general wellness information only. Talk to a clinician about your specific results.
Main source: MedlinePlus ↗
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Sources
Last updated 2026-05-02
This page presents source-specific reference data and sourced explanations. For general wellness information only. This is not medical advice. For diagnosis or treatment of any condition, talk to a qualified clinician.