Benzodiazepine Toxicity Workup

Updated: Apr 28, 2022
  • Author: J Michael Kowalski, DO; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Approach Considerations

Overall, the laboratory detection of benzodiazepines (BZDs) depends upon the screening method used. Immunoassay screening techniques are most commonly utlized. These tests typically identify BZDs that are metabolized to nordiazepam (desmethyldiazepam) or oxazepam.

Many benzodiazepines are metabolized to other compounds, however, so a negative screening result does not rule out the ingestion of a BZD. For example, alprazolam is not detected by a basic benzodiazepine urine screen.

Qualitative screening of urine or blood may be performed but rarely influences treatment decisions and has no impact on immediate clinical care. A positive test helps to confirm a suspected toxicity but a negative test does not exclude BZD ingestion. Further, a positive test in a patient without any symptoms does not equate to acute toxicity, as the test may be positive from previous use.

Tests and procedures to obtain depend on the presentation, as follows:

  • Arterial blood gas (ABG) or venous blood gas (VBG) assay, if respiratory depression is present
  • Electrocardiogram, to evaluate for co-ingestants, particularly cyclic antidepressants
  • Chest radiograph, if respiratory compromise is present
  • Pregnancy test, in women of childbearing age
  • Blood glucose level should be obtained immediately in any patient with an altered mental status

In cases of intentional overdose, measure the following:

  • Serum electrolytes
  • Liver function tests
  • Glucose
  • Blood urea nitrogen (BUN)
  • Creatinine clearance
  • Ethanol level
  • Acetaminophen level