What liver enzyme level should be monitored in a patient showing signs of acetaminophen toxicity?

Monitoring ALT (alanine aminotransferase) levels is crucial in a patient exhibiting signs of acetaminophen toxicity. Acetaminophen can cause significant liver damage, and ALT is a sensitive marker for liver cell injury. When acetaminophen is metabolized in the liver, especially in cases of overdose, it can lead to the depletion of glutathione and result in the accumulation of toxic metabolites. This can cause hepatocellular damage, reflected by elevated ALT levels in the bloodstream.

While AST (aspartate aminotransferase) is also a marker for liver injury, ALT is more specific to the liver. ALP (alkaline phosphatase) primarily indicates cholestasis and not hepatocellular damage. Bilirubin levels can increase in cases of hepatic dysfunction but are not as early or specific a marker of hepatocellular injury as ALT is. Therefore, the focus on ALT provides clinicians with a more direct insight into the extent of liver injury due to acetaminophen toxicity.