What blood test should be performed for a client starting on isoniazid (INH) for tuberculosis?

When a client is starting on isoniazid (INH) for tuberculosis, it is essential to monitor liver function, as this medication is known for its potential hepatotoxicity. Therefore, assessing liver enzymes is critical because isoniazid can cause elevated liver enzymes, indicating liver injury or dysfunction.

Routine monitoring of liver enzymes, particularly alanine aminotransferase (ALT) and aspartate aminotransferase (AST), is recommended to ensure that any liver impairment is detected early. This monitoring is particularly important in patients who have preexisting liver disease or are taking other medications that may affect liver function.

While a complete blood count is useful for assessing overall health and detecting anemia, a coagulation profile is relevant for evaluating bleeding issues, and an electrolyte panel assesses the balance of essential minerals in the body, these tests do not specifically focus on the critical concern of liver toxicity associated with isoniazid therapy. Thus, monitoring liver enzymes is the most pertinent and recommended test when initiating treatment with this antibiotic.