In acute liver failure with confusion and decreased level of consciousness, which diagnostic finding best explains this behavior?

• A. Elevated liver enzymes and low serum protein level.
• B. Subnormal clotting factors and platelet count.
• C. Elevated blood urea nitrogen and creatinine levels and hyperglycemia.
• D. Subnormal serum glucose and elevated serum ammonia levels.

Answer: (D)

When the liver fails, its ability to detoxify ammonia is lost. Ammonia produced by gut bacteria builds up in the blood, crosses into the brain, and perturbates neurotransmission, leading to cerebral edema and hepatic encephalopathy. This brain dysfunction—confusion and decreased level of consciousness in acute liver failure—is best explained by elevated serum ammonia. Subnormal glucose can occur with liver dysfunction, but it doesn’t directly account for the characteristic neuropsychiatric changes. So the diagnostic finding that most clearly explains the behavior is high ammonia levels in the blood.