Routine laboratory monitoring for serious adverse effects of antiepileptic medications: the controversy.

Rare, serious adverse effects of antiepileptic drugs (AEDs) include hepatotoxicity and bone marrow suppression. Current management includes routine laboratory monitoring during therapy with AEDs, a practice, however, that is controversial, as some clinicians believe that such monitoring is ineffective and that clinical monitoring is sufficient. Unfortunately, routine laboratory monitoring cannot predict acute idiosyncratic drug reactions, which will remain unpreventable until specific markers are available to identify susceptible patients. Nevertheless, routine laboratory monitoring may be helpful for early detection of chronic adverse reactions such as subclinical hepatotoxicity, leukopenia, or thrombocytopenia, which are usually mild and clinically insignificant but are occasionally more severe. Routine liver function tests may be especially important during valproate therapy because pathologic data suggest that some cases of valproate (VPA)-induced hepatic failure are the result of chronic liver damage and cirrhosis. Although levels of hepatic enzymes may be elevated during an early reversible stage of VPA toxicity, by the time clinical symptoms develop, hepatic failure may be irreversible.