Which liver enzyme is important to monitor if unsure about a drug's effects?

Monitoring liver enzymes is essential in assessing liver function and the impact of various medications on the liver. Alanine aminotransferase (ALT) is particularly significant because it is primarily found in the liver. An elevation in ALT levels typically indicates liver cell injury, which can occur due to drug toxicity or liver disease.

Because ALT is more liver-specific compared to other enzymes like aspartate aminotransferase (AST) or alkaline phosphatase (ALP), it gives a clearer picture of hepatic activity and potential damage. While other tests such as AST might elevate in conditions unrelated to the liver (like muscle injury), monitoring ALT levels can provide more direct insight into the liver's response to medications. This makes ALT a key enzyme to assess when unsure about the effects of a drug on liver health.

Bilirubin, on the other hand, serves as an indicator of liver function and the excretion of bile, but isn’t as sensitive to drug-induced liver injury as ALT. Thus, ALT would be the enzyme of choice for closely monitoring potential hepatic effects of medications.