Which tests are included in the workup of calcium channel blocker (CCB) toxicity?

Updated: Jan 04, 2021
  • Author: B Zane Horowitz, MD, FACMT; Chief Editor: Michael A Miller, MD  more...
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Tests to order in patients with suspected calcium channel blocker toxicity include glucose, potassium, bicarbonate, lactate, and calcium levels and an electrocardiogram (ECG). Measurement of arterial blood gases should be considered in patients with significant toxicity, to determine the acid-base status and respiratory function. Lactate levels should be considered in all hypotensive patients.

Abnormal findings may include hyperglycemia, hypokalemia, and a decreased serum bicarbonate level secondary to lactic acidosis. The calcium level is used as a baseline before administering intravenous calcium; however, patients with severe poisoning may require calcium therapy before the value becomes available.

Foley catheter placement may be indicated to monitor urine output in severely poisoned patients.

In patients who present to the emergency department (ED) after a suicide attempt, as well as those with a history of co-ingestion, laboratory tests should also include the following:

  • Serum aspirin level
  • Serum acetaminophen level
  • Urine toxicology - Results may suggest significant co-ingestants such as opiates
  • Cardiac biomarkers, such as troponin I, may help differentiate drug-induced bradycardia from ischemic causes

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