Higher than normal blood ammonia levels are called hyperammonemia. Acceptable levels depend on age and sex but range from about 100 µmol/L in infants to 16 µmol/L adults assigned male at birth.

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When you hear “ammonia,” you may think of a potent household cleaner. Interestingly, the human body produces small amounts of ammonia as well.

Keep reading to learn more about how the body makes ammonia, why it might build up and cause health issues, and ways this potentially dangerous condition is treated.

Ammonia is a nitrogen-containing waste product produced by the digestion of protein in the colon and small intestine. It is ultimately processed by the liver and removed from the body during urination.

A healthy range of ammonia can be found circulating in the blood. Too much ammonia buildup may act as a neurotoxin that damages or affects the nervous system. Without treatment, the effects on the brain can be life threatening.

Acceptable ammonia levels in the body depend on a person’s age and sex.

ageacceptable level (µg/dL)
infants under 1 month oldnot established
children 1 to 6 months old42-137
7 m to 1 y34–108
2 to 12 y33–97
13 to 30 y36-136 (males) / 29-112 (females)
31 to 40 y40-160 (males) / 30-130 (females)
41 to 50 y40-200 (males) / 31-155 (females)
51 to 70 y40-200 (males) / 34-178 (females)
71 to 80 y31-169
>80 y28-135

Acceptable levels may vary depending on the lab that processes your sample. Refer to your lab for the most precise information.

Ammonia can be tested by taking a blood sample. The amount of blood taken varies by age:

Once collected, ammonia levels in the blood can increase quickly. The most important part of the testing process is to get the sample to the lab within 20 minutes or to place the sample on ice immediately.

Ammonia is made in the colon and small intestine. It then moves to the liver to be changed into urea, a waste product. In healthy people, the urea is removed from the body through the kidneys and liver and then through urination.

When something interrupts this process, ammonia levels become elevated. This situation is referred to as hyperammonemia.

Conditions that may raise ammonia levels include:

Since ammonia is a neurotoxin, symptoms of too much ammonia in the blood can show up as either acute or chronic neurological signs. Also, they can be divided into early onset – affecting newborns under 72 hours old, and late onset – affecting children and adults.

Symptoms of early onset hyperammonemia include:

Symptoms of late onset hyperammonemia include:

When levels are very high, reaching over 200 µmol/L, it may lead to:

Treatment depends on the root cause of hyperammonemia. Decreasing the ammonia levels in the blood is the first objective in all cases.

In infants, doctors may switch from feeding with protein-containing formula/milk to solutions containing only glucose. The digestion of protein may increase ammonia. Hemodialysis is another option that filters ammonia from the blood.

Children and adults with UCD also benefit from stopping all protein foods and switching to glucose calories. Hemodialysis is an option if these measures do not reduce ammonia levels within 8 hours of starting treatment.

Doctors treat people with hepatic encephalopathy using oral medications to reduce ammonia production in the gut. The medications contain the sugars lactulose and lactitol that absorb ammonia in the intestines.

Hyperammonemia is a condition that can affect anyone – babies, children, and adults. Liver disease, specifically cirrhosis of the liver, is responsible for 90% of adult hyperammonemia cases.

The other main risk factor for hyperammonemia is having a congenital UCD.

When it’s an emergency

High ammonia levels may lead to brain herniation or swelling without prompt treatment. People with liver conditions, UCDs, and previous issues with ammonia should see their doctors routinely to monitor their ammonia levels.

Call 911 if someone you know is experiencing:

  • confusion
  • lethargy
  • rapid breathing
  • grunting (in infants)
  • unconsciousness
  • seizures
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What is the incidence of hyperammonemia?

Experts do not know the exact rate of hyperammonemia. Instead, they share that 1 in 250,000 (US) and 1 in 440,000 (internationally) have urea cycle disorders that often lead to high ammonia levels.

How can you prevent hyperammonemia?

Many health situations cause high ammonia levels. Not all can be prevented. For those who can, eating a healthy diet, exercising, and avoiding activities that may damage the liver (drinking alcohol, over-the-counter (OTC) drug use) may help.

Are there any supplements that help prevent repeat attacks?

Yes. Supplements that may help include L-carnitine, L-ornithine-L-aspartate, and arginine. Speak with a doctor before taking any supplements — they may interact with other medications you are taking.

Speak with a doctor if you have conditions that put you at risk for high ammonia levels in the blood. Hyperammonemia can be life threatening if it is not treated promptly.

Your doctor can help you identify the warning signs of an attack and where to get immediate help.