Summary

• High ammonia levels in your body can cause serious health problems.
• Ammonia is made as a normal part of digestion.
• Your liver normally helps to remove ammonia from your body but may not be able to do this if you have liver disease.
• High ammonia can also be caused by kidneys failure and some rare genetic conditions can cause high ammonia levels in newborn babies.
• If you have high ammonia levels, you can take medications to help control it.
• Ammonia level tests alone cannot diagnose Hepatic Encephalopathy (HE).

Ammonia and your liver

The liver is one of the most important organs in your body. It is essential for digesting food and changes the nutrients and chemicals in the blood into forms that are easier for your body to use. It detoxifies drugs and other substances that could be harmful and removes them from the blood.
 

If your liver is not working properly, it cannot filter waste and remove harmful toxins from your body. One of these waste products is ammonia.

Inside your digestive system is a complex community of bacteria that helps break down and process food. Most of the ammonia in your body is made by these bacteria as they help digest the protein in your diet.

Normally, a healthy liver would filter the ammonia from your bloodstream and convert it to a substance called urea which is removed from your blood by the kidneys.

If your liver is damaged and not working as it should, ammonia is not efficiently converted to urea, and it builds up in your blood. Eventually, it travels to your brain and can cause you to be confused and disorientated. Over time your symptoms worsen, and this can lead to a coma and sometimes be fatal. This is called heptatic encephalopathy. 

Why get tested?

Most cases of high levels of ammonia are in people who have liver disease. High ammonia usually happens in severe liver disease such as when you have scarring of the liver, known as cirrhosis, but you can have sudden rises in ammonia even if your long-term liver disease is stable.  High ammonia levels can also result from acute liver failure when your liver suddenly stops working properly. This can be caused by drugs, alcohol or a virus.

When ammonia builds up in the blood to the point that it affects the brain it causes a condition called hepatic encephalopathy.  This condition is graded from 0 – 4 depending on the severity of symptoms. These start with difficulty in concentrating, and mood changes, with mild confusion and anxiety, but later someone with  hepatic encephalopathy will sleep for long periods, find it difficult to talk coherently, and have seizures. Eventually, they will slip into a coma. Other substances as well as ammonia are also involved in hepatic encephalopathy. This means that ammonia testing alone cannot make a diagnosis.

If you have high ammonia levels your medical team may ask you to take a laxative that can help remove ammonia from your digestive system, or else take an antibiotic that kills the bacteria in your gut which are making the ammonia. In this way, your levels of ammonia can be controlled, and this can help manage and reduce symptoms.

Newborns and children

Urea cycle disorders (UCDs)

UCDs are rare genetic conditions that affect the urea cycle which removes ammonia from the blood. In this process, enzymes convert ammonia to urea. In people who have one of these USDs, certain enzymes that convert ammonia to urea do not work as they should or are missing altogether. Babies who have a lack of one of the urea cycle enzymes can develop extremely high ammonia levels within days of being born. Babies who are less affected may go undiagnosed until later in childhood. Moderate short-lived increases in ammonia are relatively common in newborns, where the levels may rise and fall without causing detectable symptoms. 

Reye’s syndrome

This is a rare condition that causes an increase in blood ammonia levels and a decrease in blood glucose. It mainly affects children and teenagers who are recovering from viral infections, such as chickenpox or the flu. Increased ammonia levels in children may also be due to a previously undiagnosed UCD.

Other possible causes of high ammonia

• Kidney failure when your kidneys are unable to effectively get rid of urea and it leads to a buildup of ammonia in your blood.
• Blood disorders such as multiple myeloma and acute leukemia but this is rare.
• Infections by urease-producing bacteria.
• Acute illness and seizures may cause raised blood ammonia levels, especially in children.
• Valproate, an anti-epileptic drug that can lead to increased ammonia.

Having the test

Sample

Blood.

Any preparation?

None.

Your results

Very high levels of ammonia in the blood indicate that your body is not effectively processing ammonia but do not indicate the cause.

Normal levels of ammonia do not rule out hepatic encephalopathy. Not only do other waste products contribute to the symptoms of hepatic encephalopathy, but brain levels of ammonia may be much higher than blood levels.  Therefore, ammonia levels alone cannot diagnose hepatic encephalopathy.

Ammonia testing is not useful in testing for ammonia poisoning. Ammonia acts locally, burning or irritating whatever it comes in contact with, but it does not act as a body-wide poison. 

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record.

You and your healthcare provider can now access your results whenever and wherever needed. Get further trustworthy health information and advice from healthdirect.