In the context of emergency room visits, a therapeutic drug assay for clozapine is reported with which code?

The appropriate code for a therapeutic drug assay for clozapine is 80159 because this code specifically covers therapeutic drug assays, not otherwise specified. Clozapine is an atypical antipsychotic used primarily in the treatment of schizophrenia, and monitoring its therapeutic levels is essential for effective treatment and safety due to its unique pharmacokinetics and potential adverse effects.

Code 80159 is used when testing is performed specifically for clozapine without specifying the method of testing. In contrast, other codes may pertain to different drugs or specific methodologies that do not apply to the general therapeutic testing for clozapine. Therefore, 80159 is the most accurate representation of the service provided in this scenario, as it encompasses the therapeutic drug monitoring of clozapine.