Carbamazepine Toxicity Workup

Updated: Dec 16, 2017
  • Author: Nidhi Kapoor, MD; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Laboratory Studies

See the list below:

  • Obtain a fingerstick glucose measurement for possible explanation of altered mental status.
  • Measure serum carbamazepine level to verify that symptoms are due carbamazepine toxicity. Symptomatic patients may require multiple serum levels (q4-6h) until downtrend is documented. In overdose with controlled-release carbamazepine, levels may peak as late as 96 hours after ingestion. [10]
  • Obtain serum acetaminophen level in every intentional overdose.
  • Perform liver function tests to ascertain if liver damage has occurred.
  • Obtain a complete blood count with differential (rarely, hematologic adverse effects, including agranulocytosis, thrombocytopenia, and aplastic anemia, have been reported with long-term carbamazepine use [11] )
  • Measure electrolyte levels; hyponatremia is not uncommon with chronic dosing [12] but rarely is noted in acute overdose.
  • Perform blood urea nitrogen and creatinine tests to ascertain if renal damage has occurred.
  • Measure arterial blood gas level if pulse oximetry reads less than 90-95% or if any respiratory compromise is evident.
  • Obtain a pregnancy test in females of childbearing age.

Imaging Studies

Obtain an abdominal radiograph, because patients with rising serum levels may have a bezoar of undigested tablets that may be visualized radiographically.

Obtain a chest radiograph if crackles or rales are heard on physical examination and pulmonary edema is suspected or to confirm endotracheal (ET) placement if respiratory depression occurs.


Other Tests

Obtain a 12-lead electrocardiogram (ECG). Abnormalties found may include the following [8] :

  • QRS widening
  • Sinus tachycardia
  • Varying degrees of atrioventricular block
  • QT prolongation