Our bodies are constantly working behind the scenes, aren't they? Occasionally, when these complex biological processes get disrupted, it can lead to serious health concerns. One such critical condition is Hyperammonemia, which occurs when a toxic byproduct called ammonia builds up in your blood. Because this condition can become life-threatening if not managed promptly, it is vital to stay informed about it.
What is Hyperammonemia?
Simply put, hyperammonemia is the dangerous rise of ammonia (NH3) levels in your bloodstream. Ammonia is a byproduct created in your intestines when your body digests the proteins you eat. Normally, your liver processes this ammonia through a sequence called the Urea Cycle. This cycle converts the ammonia into urea, a much less harmful substance that is safely excreted from your body in your urine.
However, if there is a disruption in this urea cycle or if your liver cannot process ammonia effectively, it begins to accumulate in your blood. High levels of ammonia in the blood are extremely toxic to your Central Nervous System (CNS)—your brain and spinal cord. This is why hyperammonemia is a medical emergency that requires immediate intervention and can be life-threatening.
Who is most at risk?
Hyperammonemia can affect anyone, from newborns and children to adults.
- Among adults, about 90% of cases are associated with Cirrhosis of the liver.
- In newborns, it can be caused by a congenital urea cycle disorder, which are inherited genetic conditions.
- In young children, it may also occur due to severe liver failure or other inherited metabolic diseases.
While the exact frequency is difficult to pinpoint due to its various causes, research suggests that as a primary condition, Urea Cycle Disorders (UCDs) affect approximately 1 in 250,000 births in the United States, and about 1 in 440,000 births internationally.
What causes Hyperammonemia?
There are several causes, which can vary by age. However, generally speaking, the two primary categories are liver dysfunction and Urea Cycle Disorders (UCDs).
Liver-Related Issues
Your liver is the primary organ responsible for converting ammonia into urea. If your liver is damaged or diseased, it loses the ability to process ammonia efficiently, causing it to build up in your blood.
Conditions that can lead to hyperammonemia include:
- Liver disease: When your liver is damaged, its ammonia-processing capacity is compromised. While more common in severe disease, even those with stable chronic liver conditions can experience sudden spikes in ammonia due to factors like gastrointestinal bleeding or electrolyte imbalances (e.g., related to salt levels). Liver disease remains the leading cause of elevated ammonia in both children and adults.
- Hepatic encephalopathy: This occurs when liver damage causes ammonia to accumulate and reach the brain, leading to symptoms like confusion, disorientation, and even coma. This can be fatal if left untreated.
- Cirrhosis of the liver:Cirrhosis involves the replacement of healthy liver tissue with scar tissue, significantly impairing liver function and potentially leading to hyperammonemia.
- Acute liver failure: This is a sudden loss of liver function. For instance, drug-induced liver injury, such as from acetaminophen overdose, accounts for 50% of acute liver failure cases in the U.S. In children, 64% of hyperammonemia cases are linked to acute liver failure.
- Decreased blood flow to your liver: If the liver does not receive adequate blood flow, it cannot effectively filter and process ammonia, leading to systemic buildup.
- Reye’s syndrome: This is a rare, serious condition that causes swelling in the liver and brain. It often causes high ammonia levels and low blood glucose. It is most commonly seen in children and teenagers recovering from viral infections like chickenpox or the flu, particularly when aspirin has been used. Because of this risk, never give aspirin to children or teenagers unless specifically directed by a doctor.
Urea Cycle Disorders (UCDs)
As mentioned, the urea cycle is the process of converting toxic ammonia into urea. This process involves several steps, each requiring a specific enzyme, including:
- N-acetyl-glutamate synthase (NAGS)
- Carbamoyl phosphate synthetase (CPS)
- Ornithine transcarbamylase (OTC)
- Argininosuccinate synthetase (AS)
- Argininosuccinic acid lyase (ASL)
- Arginase (ARG1)
If any of these enzymes are deficient, the cycle fails, and ammonia accumulates. These genetic conditions, known as UCDs, can cause both acute and chronic hyperammonemia.
UCDs are present from birth. Newborns with a complete enzyme deficiency typically develop acute hyperammonemia within 24 to 72 hours of birth. If the deficiency is partial or mild, symptoms may trigger later in life due to illness or stress. UCDs are responsible for 23% of acute hyperammonemia cases in severely ill children.
Other Causes
Beyond the factors mentioned above, there are several other potential causes:
- Kidney (renal) failure: When your kidneys fail, they cannot effectively filter urea from your body. This causes ammonia to build up in your bloodstream.
- Certain blood disorders: Conditions such as multiple myeloma and acute leukemia can also trigger hyperammonemia.
- Certain infections: Infections caused by urease-producing organisms—such as Proteus mirabilis, Escherichia coli (E. coli), and Klebsiella—can lead to severe hyperammonemia. This is particularly common in children born with urinary tract defects or in older adults suffering from urinary retention due to UTIs.
What are the symptoms of Hyperammonemia?
Symptoms can vary significantly based on your age and the severity of your condition.
Common mild symptoms in children and adults
- Nausea and vomiting
- Abdominal pain
- Irritability
- Headache
- Difficulty with balance, coordination, or speech (ataxia)
- Behavioral changes
Additional mild symptoms specific to children
- Failure to thrive
- Muscle weakness (hypotonia)
- Neurodevelopmental delays
Severe symptoms in children and adults
These are serious warning signs. If you experience any of these, seek medical attention immediately.
- Confusion and disorientation
- Mood swings
- Excessive sleepiness
- Changes in consciousness
- Seizures
- Hyperventilation (rapid breathing)
- Coma
Warning: If you or a loved one are experiencing these symptoms, please call 911 immediately or proceed to the nearest hospital emergency department. High levels of ammonia in the blood are life-threatening and require urgent medical intervention.
Symptoms in newborns
In newborns, hyperammonemia typically presents between 24 and 72 hours after birth:
- Irritability and excessive crying
- Vomiting
- Lethargy
- Seizures
- Grunting when breathing
- Hyperventilation
Important: If your baby displays these symptoms while you are still in the hospital, notify your doctor immediately. If you are at home, call 911 or go to the nearest emergency room immediately. Do not delay seeking care.
How is this diagnosed by the Nirogi Lanka medical team?
Doctors typically suspect hyperammonemia by checking your blood ammonia levels.
- For babies up to one month old: Levels higher than 80 micromol/L are concerning.
- For older children: Levels higher than 55 micromol/L are concerning.
- For adults: Levels higher than 30 micromol/L are concerning.
Micromol/L is the standard unit used to measure the amount of ammonia in your blood.
Diagnostic tests
The primary diagnostic tool is a blood test to measure ammonia levels.
If high levels are confirmed, your doctor may order additional tests to identify the underlying cause, such as liver function tests, kidney function tests, or a urinalysis.
Because hyperammonemia can damage the central nervous system and pose a threat to life, your doctor may also recommend imaging tests like a CT (computed tomography) scan or an MRI (magnetic resonance imaging) to check for neurological complications.
What are the treatments for Hyperammonemia?
Treatment depends entirely on the underlying cause—whether it is hepatic encephalopathy in an adult with liver disease, or a urea cycle disorder (UCD) in a newborn.
In cases of acute hyperammonemia, the goal is to lower blood ammonia levels rapidly and manage complications such as cerebral edema (brain swelling) and intracranial hypertension.
- For newborns, doctors will stop protein intake (as protein digestion produces ammonia) and provide calories through glucose solutions. Hemodialysis may be used to clean the blood using a specialized machine and filter (acting as an artificial kidney).
- For those with partial UCD enzyme deficiency triggered by stress, protein intake is restricted while glucose provides caloric support. Hemodialysis is reserved for cases where initial treatment fails to lower ammonia levels within a few hours.
- To treat hepatic encephalopathy, the focus is on reducing ammonia production in the intestines. First-line treatments include oral medications containing lactulose or lactitol, which help prevent the body from absorbing ammonia.
For those with chronic urea cycle disorders, doctors may prescribe specific dietary supplements to prevent recurrence, including:
- L-carnitine
- L-ornithine-L-aspartate
- Arginine
Can this condition be prevented?
Because hyperammonemia has various causes, it cannot always be prevented. However, you can take steps to protect your liver and overall health:
- Avoid or limit alcohol consumption.
- Minimize intake of trans fats and high-fructose corn syrup.
- Be cautious with both prescription and over-the-counter medications to avoid liver strain.
- Maintain a consistent exercise routine.
- Limit the consumption of red meat.
To help prevent Reye’s syndrome in children and teenagers—a condition that can lead to hyperammonemia—never give aspirin for viral symptoms (such as fever or chickenpox) unless explicitly directed by a doctor.
Urea Cycle Disorders (UCDs) are rare, but genetic tests are available to determine if you carry the genes responsible for these conditions. Please consult your physician to discuss whether this screening is appropriate for you.
What is the prognosis for this condition?
The prognosis for hyperammonemia—or your outlook for recovery—depends on several critical factors:
- The severity of your ammonia elevation.
- The duration for which your ammonia levels have remained elevated.
- The underlying medical cause of the hyperammonemia.
Generally, the prognosis for hyperammonemia can be guarded. If treatment is delayed or not administered, irreversible brain swelling can lead to a high mortality rate. Unfortunately, in newborns with severe hyperammonemia, even aggressive and immediate intervention does not always guarantee a positive outcome.
In the United States, patients with UCDs who experience hyperammonemia early in life have an 11-year survival rate of approximately 35%. For those who develop hyperammonemia later in life, this survival probability rises to approximately 87%.
For individuals who develop severe hepatic encephalopathy due to hyperammonemia, survival rates at one and three years have been reported at 42% and 23%, respectively.
What are the possible complications of hyperammonemia?
If this condition is not treated promptly, elevated ammonia levels can damage the central nervous system, leading to life-threatening complications, including:
- Cerebral edema (brain swelling)
- Intracranial hypertension (increased pressure within the skull)
- Brain herniation – often a result of severe brain swelling and increased pressure.
- Coma
- Death
If you experience chronic mild hyperammonemia, you may be at risk for long-term intellectual disabilities and persistent behavioral or psychiatric challenges.
When should you see a doctor?
If you or a loved one exhibit symptoms of hyperammonemia, call 911 or proceed to the nearest emergency department immediately. Do not delay seeking care.
If you have liver disease or a partial deficiency in urea cycle enzymes, it is vital to maintain regular check-ups with your physician to manage your condition and monitor your ammonia levels effectively.
Hyperammonemia is a serious condition with various underlying causes. If you, your child, or an infant shows symptoms, seek medical help immediately. If you have liver disease or a family history of UCDs, discuss your personal risk factors with your doctor. Nirogi Lanka is here to support you in your health journey.
Final thoughts to keep in mind
To summarize, here are the most important points to remember:
- Hyperammonemia occurs when blood ammonia levels rise to dangerous levels, which is highly toxic to your brain and nervous system.
- It has multiple potential causes, with liver dysfunction and Urea Cycle Disorders (UCDs) being the primary contributors.
- Symptoms vary by age and severity, ranging from mild issues like nausea, vomiting, and headaches to severe manifestations such as confusion, seizures, and coma. Always be vigilant regarding symptoms in newborns.
- In the presence of severe symptoms, seek medical attention instantly. This can be a life-or-death situation.
- Treatment is tailored to the root cause. Rapid intervention focuses on lowering ammonia levels and managing complications.
- While some causes cannot be prevented, maintaining a healthy lifestyle and monitoring your liver health can help reduce certain risks.
- If you suffer from liver disease or have a family history of UCDs, regular medical screenings are essential.
Remember, you know your health best. If you notice any unusual changes or symptoms, do not hesitate to consult a doctor. We are here to help.
Hyperammonemia, ammonia, liver, urea cycle, brain, symptoms, treatment
