Elevated Blood Ammonia Level: What It Means and What to Do

Medically Reviewed By Kevin Martinez, M.D.
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Blood ammonia level refers to the amount of the waste compound ammonia present in the blood. An elevated blood ammonia level points to too much accumulation of ammonia, which can be toxic. An elevated blood ammonia level can have fatal complications and may be a sign of underlying disease. A high blood ammonia level can occur at any age and can happen for a variety of reasons. It may be the result of genetic conditions, lifestyle factors, or diseases.

Read on to learn more about how blood ammonia levels increase, as well as the causes, treatment, and prevention of the condition.

What is an elevated blood ammonia level?

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Ammonia is a waste compound that the body produces during protein digestion. Typically, the liver will process ammonia and turn it into another waste product called urea, which the body then excretes in urine.

An elevated blood ammonia means that the body is not processing or excreting the ammonia, so it instead builds up in the bloodstream. Clinicians may refer to this condition as hyperammonemia.

Buildup of ammonia in the blood can be dangerous because excess ammonia in the blood is toxic. Complications of too much ammonia in the blood can be fatal.

Seek prompt medical care if you are undergoing treatment for an elevated blood ammonia level and your symptoms recur or persist, or for anyone with severe symptoms.

Severe symptoms may include:

  • seizures
  • changes in behavior
  • lapses into unconsciousness
  • difficulty breathing

What are the symptoms of an elevated blood ammonia level?

Symptoms of a high blood ammonia level may relate to impaired liver or kidney function.

When waste products such as ammonia build up in the blood, they can circulate throughout the body and act as toxins.

Too much ammonia can act as a toxin to the central nervous system (CNS). Due to the neurotoxicity of ammonia, hyperammonemia can cause neurological signs and symptoms.

Some who experience an elevated ammonia level may only develop symptoms when the body is in periods of stress. For example, this may include during pregnancy, surgery, or starvation.

However, as the disease progresses, you may experience more symptoms or symptoms of increased severity.

Symptoms

Signs or symptoms of a high blood ammonia level can include:

Children may present any of these signs or symptoms, as well as having trouble breathing or presenting low or lower responsiveness than is typical for them.

Symptoms that might indicate a serious condition

In some cases, an elevated blood ammonia level can be the result a serious condition that requires immediate treatment in an emergency setting. 

Seek immediate medical care or call 911 for anyone experiencing serious symptoms, including:

What is an ammonia levels test?

The ammonia levels test will measure the amount of ammonia in the blood.

To do this, a nurse or doctor will use a needle to take a blood sample to study. They will collect a small amount of blood from a vein in the arm. In rare cases, clinicians may want to sample arterial blood, which may involve taking the sample from the wrist, elbow, or groin.

In infants, the clinician may take the sample from the heel of the foot.

In newborns, an elevated blood ammonia level may present with signs and symptoms that are non-specific to the condition. Testing to rule out other serious conditions is important.

Special preparations may be necessary to undergo an ammonia levels test, such as avoiding exercise or smoking cigarettes for around 8 hours beforehand. Your doctor can advise you on how to prepare.

There is little risk to the test, but you may experience minimal pain or bruising around the area.

If necessary, a clinician may test other factors to help diagnose a condition, including testing for electrolytes and performing liver function tests.

Who needs an ammonia levels test?

Anyone presenting symptoms of elevated blood ammonia levels should have an ammonia levels test. This can help to diagnose a condition that may be causing a high ammonia level, or to check whether your levels are safe if you are experiencing symptoms of ill health.

If you already have other conditions that affect organ function or are aware that you have a condition that causes high ammonia, you may also undergo ammonia levels testing to monitor your condition.

What is a critical ammonia level?

Your test results can vary depending on factors such as the test method used to study blood ammonia levels or any medication you take. This may mean that even if your results indicate levels outside of the standard range, you may not have an underlying condition.

If you are unsure about the meaning of your results or have any questions, contact your doctor.

If your test shows that you do have high levels of ammonia in the blood, it could signal you have an underlying health condition.

In this case, you will need further testing and examination to determine the cause of your elevated blood ammonia level. Your doctor will develop a treatment plan with you accordingly.

Expected ranges of ammonia levels in individuals without high blood ammonia levels include:

AgeRange
Infants born at healthy term36 to 54 micromol/L
Infants born preterm45 to 97 micrmol/L, decreasing to healthy term levels by approximately 7 days
Children over 1 month oldless than 50 micromol/L
Adults less than 30 micromol/L

What causes a high blood ammonia level?

An elevated blood ammonia level may occur as a result of a variety of conditions, including hereditary defects, acquired diseases, and organ damage, as well as a few behavioral factors.

Causes in infants may include congenital and prenatal as well as acquired conditions.

Causes may include:

  • liver disease or failure, such as hepatic encephalopathy, cirrhosis, or hepatitis
  • newborn hemolytic disease, in which the gestational carrier’s body develops antibodies to the baby’s blood cells
  • urea cycle disorder
  • urinary tract infection, congenital defect, or disorder
  • gastrointestinal bleeding
  • increased protein load through IV administration of nutrition
  • increased muscle catabolism (for example, due to seizure or starvation)
  • infection
  • drug and alcohol use
  • hematological disorders, such as myeloma or leukemia
  • certain medications including carbamazepine, an epilepsy treatment, and sulfadiazine, an antibiotic
  • response to salicylates, natural chemicals found in plants and certain medications
  • Reye’s syndrome, a potentially fatal disease that can affect the liver and brain
  • kidney failure
  • inborn disorders of the metabolism
  • dysfunction of the metabolic system
  • hemolysis, the destruction of blood cells
  • use of tourniquets
  • smoking
  • sepsis

For more information on liver disease, including specific conditions, symptoms, causes, and treatments, read on here.

Risk factors

Certain factors may increase the risk of developing an elevated blood ammonia level. However, not all people with risk factors will experience an elevated blood ammonia level.

Investigating the incidence of hyperammonemia with other conditions, researchers of a 2020 analytic study of retrospective data observed evidence for the following conditions as risk factors for high ammonia levels:

  • obesity
  • high protein diets in those with obesity
  • consumption of particular drugs and medicine, such as valproic acid (used to treat epilepsy) and corticosteroids
  • damage to skeletal muscle
  • orthopedic surgery that results in damage to skeletal muscle
  • bacterial infection

The researchers note that they were unable to determine the causal relationship between serum ammonia level and the severity of illness. This means that they do not know whether higher ammonia levels directly result in more severe ill health.

Risk factors for an elevated blood ammonia level that results from liver disease may also include obesity, alcohol misuse, and infections such as hepatitis.

Reducing your risk of an elevated blood ammonia level

You may be able to lower your risk of experiencing an elevated blood ammonia level as a result of acquired disease or behavioral factors by reducing your risk of liver disease.

Steps you can take to decrease the risk of liver disease include:

  • avoiding substance misuse
  • following your doctor’s advice on any medication or drugs you take and their dosages
  • maintaining a moderate weight
  • avoiding alcohol
  • vaccinating yourself against hepatitis A and hepatitis B
  • eating a balanced diet
  • exercising regularly
  • optimizing care for conditions that may lead to liver disease
  • undergoing liver disease screenings as your doctor advises

How do you get rid of ammonia in the body?

Treatment for an elevated blood ammonia level aims to decrease the level of ammonia in the blood and control for any potential complications. Treatment also addresses the underlying cause of the condition.

Treatment will depend on the cause and severity of a person’s condition.

Treatment options to decrease a high blood ammonia level include:

  • Elimination of protein intake for neonates: Reduction of protein intake may treat newborns with inborn metabolic causes of hyperammonemia who experience coma.
  • Hemodialysis: A dialysis machine and a machine known as an artificial kidney cleans the blood.
  • Hemofiltration: This involves the removal of harmful solutes in plasma and the administration of a clean replacement fluid.
  • Drugs: Compounds such as sodium benzoate and phenylacetate can convert waste compounds into products that the body can eliminate.
  • IV nutrition: Clinicians may apply nutritional solutions such as stopping nitrogen intake and providing calories via glucose solutions by IV.
  • Dietary management: Certain compounds such as L-carnitine and L-ornithine-L-aspartate can supplement the diet to decrease frequency of occurrence, as well as increasing the metabolism of ammonia in the muscles.
  • Management of possible complications: Your medical team will provide treatment for any potential complications you may experience.
  • Treatment for hepatic encephalopathy: This can include antibiotics as well as oral treatments that can decrease the production and absorption of ammonia.

Further investigation and treatment may be necessary to address the underlying condition that caused the high blood ammonia level.

What are the potential complications of an elevated blood ammonia level?

As an elevated blood ammonia level is the result of waste building up in the bloodstream, it can cause damage to your internal organs or brain tissue.

Complications of untreated or poorly controlled elevated blood ammonia levels can be life threatening.

It is very important to carefully follow your doctor’s recommended treatment plan to minimize your risk of serious complications.

Potential complications of an elevated blood ammonia level include:

  • further or secondary disease due to toxicity, including respiratory alkalosis and encephalopathy
  • impaired cognitive function
  • damage to the CNS
  • raised intracranial pressure
  • brain herniation
  • coma
  • metabolic acidosis, an imbalance of the body’s acidic state
  • death

Summary

An elevated blood ammonia level, also known as hyperammonemia, is the accumulation of the waste compound ammonia in the bloodstream. This buildup can be fatal.

High ammonia levels in the blood can happen due to underlying inborn or acquired diseases and lifestyle factors that impact the function of organs such as the liver and kidneys. Individuals of any age may experience an elevated blood ammonia level.

Treatment focuses on getting rid of ammonia from the blood and addressing the underlying cause.

Seek immediate medical help for any symptoms of high blood ammonia levels, including serious symptoms of seizure, behavioral changes, and difficulty breathing.

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Medical Reviewer: Kevin Martinez, M.D.
Last Review Date: 2022 Apr 12
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