Monoamine Oxidase Inhibitor (MAOI) Toxicity Workup

Updated: Oct 25, 2023
  • Author: Eddie Garcia, MD; Chief Editor: Michael A Miller, MD  more...
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Laboratory Studies

Standard laboratory tests for poisoned patients are indicated if the patient has significant symptoms. Such tests may include the following:

  • Rapid bedside glucose determination
  • Arterial blood gas determination - Indicated if a compromise in oxygenation or ventilation is suspected
  • Lactate level - May be useful in phases 2 and 3 of an acute overdose to help determine end-organ perfusion
  • Determination of serum electrolyte, calcium, and magnesium levels - Calculation of the anion gap possibly helpful in screening for co-ingestions (see the Anion Gap calculator)
  • Serum acetaminophen level and salicylate level - Indicated in intentional overdoses
  • Screening for serum levels of alcohol (ethanol, methanol, isopropyl alcohol) - Indicated if alcohol ingestion is clinically suspected
  • Urine pregnancy test - Indicated in all women of childbearing age
  • Urinalysis and urine pH determination - May be useful in the setting of rhabdomyolysis
  • Urine drug screening - Comprehensive drug screening and screening for commonly abused drugs is possibly helpful in assessing co-ingestions

Quantitative levels of monoamine oxidase inhibitors are not readily available and, therefore, are not clinically useful. Consider workup for hypertensive emergencies if any signs or symptoms are present.


Imaging Studies

Chest radiography is indicated if aspiration is a concern. Perform postintubation chest radiography to evaluate the position of the endotracheal tube in relation to the carina if respiratory support is needed.