Ammonia (NH3)

Ammonia, Plasma

The Ammonia (Plasma) test measures the level of ammonia in the blood. Ammonia is a waste product formed when the body breaks down protein. Normally, the liver converts ammonia into urea, which is excreted in urine. Elevated ammonia levels can indicate serious liver dysfunction or inherited metabolic disorders.

1. What Is Ammonia?

• Ammonia is a nitrogen-containing compound produced during protein metabolism.

• It is toxic in high amounts and is normally converted to urea by the liver for safe elimination.

• When the liver is not functioning properly, ammonia can accumulate in the bloodstream, potentially leading to confusion, lethargy, or coma.

2. Why Is the Ammonia Test Performed?

The test is ordered to:

• Diagnose or monitor hepatic encephalopathy (a brain disorder caused by liver failure).

• Evaluate unexplained changes in mental status or consciousness.

• Detect inherited urea cycle disorders in infants and children.

• Assess the severity of liver disease or cirrhosis.

3. Ammonia Reference Ranges

• Normal range (adults): 15 – 45 µg/dL (micrograms per deciliter)

• Reference ranges may vary slightly between laboratories and age groups.

4. How to Interpret Ammonia Results

🔹 Elevated Ammonia:

• May indicate liver failure, hepatic encephalopathy, or Reye's syndrome (in children).

• Can be caused by genetic urea cycle disorders that prevent the breakdown of ammonia.

🔹 Normal Ammonia:

• Suggests that ammonia metabolism is functioning normally, even in cases of mild liver disease.

5. What Can Affect Ammonia Levels?

• Liver diseases (cirrhosis, hepatitis, acute liver failure)

• Gastrointestinal bleeding

• Excessive protein intake or catabolism

• Certain medications (e.g., valproic acid)

• Genetic metabolic disorders (especially in newborns)

6. How to Prepare for the Test and Ensure Accuracy

• Fasting may be required—follow your provider's instructions.

• Avoid smoking or physical exertion before the test, as these may affect results.

• The blood sample must be processed quickly and kept on ice to avoid falsely elevated readings.

7. When to See a Doctor

🚨 Seek medical attention if you or a loved one experiences:

• Sudden confusion or disorientation

• Lethargy or difficulty staying awake

• Symptoms of liver failure or unexplained vomiting (especially in children)

🔹 Key Takeaways

✅ Ammonia is a toxic byproduct of protein metabolism, normally removed by the liver.

✅ Elevated levels suggest liver dysfunction or a metabolic disorder.

✅ Prompt testing and treatment are crucial for high ammonia levels, especially in altered mental status.