Theophylline Toxicity Workup

Updated: Apr 29, 2020
  • Author: Greg Hymel, MD; Chief Editor: Stephen L Thornton, MD  more...
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Laboratory Studies

Obtain serum theophylline level upon presentation and then every 2 hours until the level falls. This is especially important following ingestion of extended-release formulations. Theophylline can form bezoars, resulting in ongoing absorption and toxicity despite general measures at GI decontamination.

WBC can be elevated (due to increased catecholamine activity).

Obtain acetaminophen (paracetamol) level.

Obtain aspirin (ASA) level, particularly in patients with history and findings suggestive of aspirin toxicity, including but not limited to metabolic acidosis, respiratory alkalosis, and change of mental status.

Order electrolytes and glucose tests to evaluate for the following:

  • Hypokalemia (serial testing of serum potassium levels may be required)

  • Hyperglycemia

  • Metabolic acidosis (lactate)

  • Hypocalcemia/hypercalcemia

  • Hypophosphatemia

  • Ketosis

Test for pregnancy in women of childbearing age.


Imaging Studies

A CT scan of the brain is indicated if seizures occur.


Other Tests

Electrocardiogram is performed to look for evidence of electrolyte abnormalities and dysrhythmias. Also, ECG should be used to evaluate for the signs of TCAs or other cardioactive drug toxicity.

Lumbar puncture may be required for the evaluation of new-onset seizures.