What is the role of lab studies in the evaluation of carbon monoxide (CO) toxicity?

Updated: Sep 18, 2018
  • Author: Guy N Shochat, MD; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Answer

Other test results include the following:

  • Creatinine kinase, urine myoglobin - Nontraumatic rhabdomyolysis can result from severe CO toxicity and can lead to acute renal failure.

  • Complete blood count - Mild leukocytosis may be present; disseminated intravascular coagulation (DIC) and thrombotic thrombocytopenic purpura (TTP) require further hematologic studies.

  • Electrolytes and glucose level - Hypokalemia and hyperglycemia occur with severe intoxication.

  • Blood lactate level - Elevation is an indication of severity, [3, 28]  and may correlate with neurologic outcomes. [29]  If the source of the CO was a house fire and the lactate level is 10 mmol/L or higher, the patient may have concomitant cyanide poisoning. [3]

  • Blood urea nitrogen (BUN) and creatinine levels - Acute kidney failure may result from myoglobinuria.

  • Liver function tests - Mild elevation in fulminant hepatic failure

  • Urinalysis - Positive for albumin and glucose in chronic intoxication

  • Methemoglobin level - Included in the differential diagnosis of cyanosis with low oxygen saturation but normal PaO2

  • Toxicology screen - For instances of suicide attempt

  • Ethanol level - A confounding factor of both intentional and unintentional poisonings

  • Cyanide level - If cyanide toxicity also is suspected (eg, industrial fire); cyanide exposure is suggested by an unexplained metabolic acidosis; rapid determinations rarely are available. Smoke inhalation is the most common cause of acute cyanide poisoning.


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