Description
Why It’s Done:
This test is typically ordered to:
• Evaluate liver function, especially in cases of:
o Hepatic encephalopathy (confusion, drowsiness, or coma due to liver dysfunction)
o Liver failure, cirrhosis, or hepatitis
• Investigate unexplained changes in mental status, such as confusion or lethargy
• Diagnose urea cycle disorders (rare inherited conditions affecting ammonia processing, especially in infants)
• Monitor patients with known liver disease
Preparation:
• Fasting: You may be asked to fast for 6–8 hours before the test.
• Avoid smoking and strenuous exercise before the test, as these can increase ammonia levels.
• Inform your doctor about all medications, including:
o Diuretics
o Valproic acid
o Chemotherapy drugs
o Alcohol consumption
Important Note:
Proper handling of the blood sample is crucial. It must be:
• Collected in a chilled tube
• Placed on ice immediately
• Processed quickly to prevent false elevation of ammonia levels
