In Reye syndrome, which laboratory finding is typically elevated?

In Reye syndrome, which laboratory finding is typically elevated?

• A. Serum AST
• B. Serum ALT
• C. Plasma ammonia
• D. Serum bilirubin

Answer: (C)

In Reye syndrome the liver fails to detoxify ammonia because of acute hepatic dysfunction, so ammonia accumulates in the blood. This hyperammonemia is the characteristic finding that directly links to the brain symptoms seen in the syndrome, such as encephalopathy, vomiting, and confusion. While liver enzymes like AST and ALT can be elevated due to hepatocellular injury and bilirubin may rise as damage progresses, the most distinctive and clinically important lab abnormality is elevated plasma ammonia, reflecting impaired urea cycle function and liver failure.

In Reye syndrome the liver fails to detoxify ammonia because of acute hepatic dysfunction, so ammonia accumulates in the blood. This hyperammonemia is the characteristic finding that directly links to the brain symptoms seen in the syndrome, such as encephalopathy, vomiting, and confusion. While liver enzymes like AST and ALT can be elevated due to hepatocellular injury and bilirubin may rise as damage progresses, the most distinctive and clinically important lab abnormality is elevated plasma ammonia, reflecting impaired urea cycle function and liver failure.