What lab test should be monitored when using methotrexate?

When using methotrexate, monitoring liver function is crucial due to the drug’s potential hepatotoxic effects. Methotrexate can cause liver enzyme elevations and, in some cases, lead to liver damage or fibrosis, especially with long-term use or in patients with pre-existing liver conditions.

Regular assessments of liver enzymes, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), help identify any early signs of liver injury, allowing for timely intervention. This is particularly important in managing the risks associated with methotrexate therapy, which is commonly used in the treatment of various autoimmune diseases and certain cancers.

Other tests, such as monitoring kidney function or a complete blood count, are also important in the context of methotrexate therapy but do not specifically target the primary risk posed by the medication as directly as liver function tests do. For instance, while kidney function monitoring is essential due to methotrexate's potential nephrotoxicity, it is liver function that requires the most careful and regular evaluation to prevent serious complications.