Baseline liver enzyme testing is required before starting isoniazid and how often thereafter?

Baseline liver enzyme testing is required before starting isoniazid and how often thereafter?

• A. Monthly
• B. Weekly
• C. Biweekly
• D. Quarterly

Answer: (A)

Isoniazid can cause hepatotoxicity, so you want a baseline measure of liver function before starting therapy to know if there is already liver impairment. Once therapy begins, monthly liver enzyme testing is recommended because the risk of isoniazid-related liver injury can develop during treatment, sometimes suddenly. Regular monthly checks help detect even asymptomatic rises in liver enzymes early, allowing you to pause or adjust treatment before meaningful liver damage occurs. The risk is higher in older patients, those with preexisting liver disease, or with alcohol use, which is why ongoing monitoring is important. If someone develops symptoms such as fatigue, abdominal pain, or jaundice, or if enzymes rise significantly, you’d reassess immediately.

Isoniazid can cause hepatotoxicity, so you want a baseline measure of liver function before starting therapy to know if there is already liver impairment. Once therapy begins, monthly liver enzyme testing is recommended because the risk of isoniazid-related liver injury can develop during treatment, sometimes suddenly. Regular monthly checks help detect even asymptomatic rises in liver enzymes early, allowing you to pause or adjust treatment before meaningful liver damage occurs. The risk is higher in older patients, those with preexisting liver disease, or with alcohol use, which is why ongoing monitoring is important. If someone develops symptoms such as fatigue, abdominal pain, or jaundice, or if enzymes rise significantly, you’d reassess immediately.