Ammonia: High Levels in Blood Explained

What Is Ammonia?

Ammonia is a waste chemical made in your body when protein is broken down. Bacteria in the intestines and your body’s cells both produce it.

Normally, the liver removes ammonia from the blood by turning it into urea. The kidneys then remove urea through urine. This keeps ammonia levels low and safe.

If the liver or kidneys cannot clear ammonia properly, ammonia in blood can build up. High ammonia levels can affect the brain and lead to serious neurological symptoms. This is why the ammonia blood test is often used when doctors suspect liver-related brain problems, such as hepatic encephalopathy.

When Is Ammonia Testing Recommended?

The ammonia test is usually ordered when excess ammonia may be affecting the brain or when liver failure is suspected.

Common reasons include:

• Sudden confusion or changes in consciousness
• Unexpected coma or severe neurological symptoms
• Suspected hepatic encephalopathy
• Severe liver disease or liver failure
• Kidney failure with toxin buildup
• Screening for rare urea cycle disorders
• Suspected Reye syndrome in children
• Persistent vomiting and extreme tiredness in a child after a viral illness

How Is Ammonia Testing Conducted?

Ammonia levels are measured through a blood test. A healthcare provider draws blood from a vein in your arm using a needle.

The sample is sent to a laboratory to check the ammonia level in the bloodstream. Because ammonia can change quickly, proper sample handling is important for accurate results.

No major preparation is needed, but your doctor may give a few instructions.

Before the ammonia blood test, you may be asked to:

• Avoid smoking
• Avoid intense exercise
• Share all supplements and substances you take regularly

What Are the Normal Ammonia Levels?

Normal ammonia levels depend on age and the laboratory method used.

Typical normal ranges include:

• Age 0 to 10 days: 170 to 341 mcg/dL
• 10 days to 2 years: 68 to 136 mcg/dL
• Children older than 2 years: 19 to 60 mcg/dL
• Adults: 10 to 80 mcg/dL

Note: The units of measurement and the normal ranges can differ depending on the laboratory and the specific methods used.

What Do High Ammonia Levels Mean?

High ammonia levels, also called elevated ammonia levels, mean that the body is unable to remove ammonia from the blood efficiently. When ammonia in the blood rises, toxins can affect brain function.

Possible causes include:

• Liver disease: A damaged liver cannot convert ammonia into urea properly.
• Hepatic encephalopathy: Excess ammonia interferes with brain activity and may cause confusion or coma.
• Kidney failure: Waste products can build up when kidney function is reduced.
• Urea cycle disorders: Rare genetic conditions prevent normal ammonia clearance.
• Reye syndrome: A serious condition in children that affects the liver and brain.
• Portacaval shunt: Altered blood flow in the liver may cause ammonia levels to rise.

Recommendations

• Seek urgent medical care for confusion, severe fatigue, or seizures.
• Follow your doctor’s plan for evaluating liver and kidney function.
• Avoid alcohol and substances that stress the liver if advised.
• Monitor ammonia levels through follow-up testing when recommended.

Which Specialist Should You Consult?

The right specialist depends on the cause of abnormal ammonia levels.

You may be referred to:

• A hepatologist for liver disease and hepatic encephalopathy
• A neurologist for brain-related symptoms
• A nephrologist for kidney failure concerns
• A genetic specialist for suspected urea cycle disorders in children