Theophylline Toxicity Workup

Updated: Jan 07, 2016
  • Author: Greg Hymel, MD; Chief Editor: Asim Tarabar, 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

See the list below:

  • Obtain a CT scan of the brain if seizures occur.

Other Tests

See the list below:

  • Electrocardiogram, looking 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.