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Lab Test: Cyanide (Blood) Level

    Lab Test
    • Cyanide (Blood)
    Description
    • Measurement of cyanide level in blood or serum following intentional or inadvertent exposure
    Reference Range
    • Smokers:
      • Serum:  0.006 mg/L (0.23 micromol/L)
      • Blood (fluoride/oxalate):  0.041 mg/L (1.57 micromol/L)
    • Nonsmokers:
      • Serum:  0.004 mg/L (0.15 micromol/L)
      • Blood (fluoride/oxalate):  0.016 mg/L (0.61 micromol/L)
    • Nitroprusside therapy:
      • Serum:  0.01-0.06 mg/L (0.38-2.3 micromol/L)
      • Blood (fluoride/oxalate):  0.05-0.5 mg/L (1.92-19.2 micromol/L)
    Indications & Uses

    • Suspected cyanide toxicity in smoke inhalation victims - cyanide levels of 1 mcg/mL (38.5 micromol/L) or greater are typically associated with significant symptoms.  The length of exposure to carbon monoxide does not always correlate with a specific cyanide level. 
    • Suspected cyanide exposure or poisoning - elevated blood cyanide levels may confirm the diagnosis of cyanide poisoning but are not always clinically use3ful unless results are rap-idly available.  Treatment should be initiated based on clinical presentation and index of suspicion. 
    • Whole blood cyanide levels and associated symptoms:
      • 0.5-1 mcg/mL (20-38 micromol/L):  tachycardia, flushing
      • 1-2.5 mcg/mL (48-95 micromol/L):  depressed level of consciousness
      • 2.5-3 mcg/mL (95-114 micromol/L):  coma, respiratory depression >3 mcg/mL (>114 micromol/L):  death

    Procedure
    • Prolonged time from specimen collection to analysis will result in falsely low readings
    Storage and Handling
    • Store sample at 4°C to 8°C°
    References
    • LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests.  First ed. Montvale, NJ: Thomson PDR; 2007.

MESH Terms & Keywords

  • Cyanide