Why get tested?
To detect elevated levels of ammonia in the blood, to evaluate changes in consciousness, or to help diagnose hepatic encephalopathy and Reye’s syndrome

When to get tested?
If a patient experiences mental changes or lapses into a coma of unknown origin; if an infant or child experiences frequent vomiting and increased lethargy as a newborn or about a week after a viral illness

Sample required?
A blood sample drawn from a vein or artery in your arm