title: Effects of hydroxocobalamin on carboxyhemoglobin measured under physiologic and pathologic conditions.
abstract: BACKGROUND
  Pre-hospital administration of hydroxocobalamin (B12a) is used for empiric treatment of cyanide poisoning because cyanide poisoning is difficult to identify and requires immediate treatment. B12a interferes with the accuracy of several blood laboratory tests. This study aimed to explore how B12a affects carboxyhemoglobin (COHb) measurements in human blood at both physiologic and pathologic COHb levels.
  
  
  METHODS
  Several clinically relevant concentrations of B12a were added to human blood samples containing physiologic (∼ 3%) and pathologic (30% and 50%) COHb levels. We then measured the COHb levels of the samples using two different co-oximeters, the Radiometer ABL 700 and the Rapidpoint 500, and compared to their actual baseline COHb levels.
  
  
  RESULTS
  B12a had minimal effects on the COHb measured at both physiologic and pathologic levels when measured on the Radiometer. In contrast, the Rapidpoint B12a caused a dose-dependent decrease in the COHb measured, especially of pathologic COHb levels (∼ 30 and 50%).
  
  
  CONCLUSIONS
  The magnitude of B12a interference on measured COHb is dependent upon the specific co-oximeter used, the actual COHb level and the serum B12a concentration. These errors may potentially influence clinical decision making and thus affect patient outcomes. Our findings emphasize the importance of measuring COHb levels on blood samples collected prior to B12a administration.
authors.affiliation: Department of Mental Health and Hygiene, New York City Poison Control Center , New York, NY , USA.
authors.forename: R
authors.initials: R
authors.lastname: Pace
authors.forename: M
authors.initials: M
authors.lastname: Bon Homme
authors.forename: R S
authors.initials: RS
authors.lastname: Hoffman
authors.forename: D
authors.initials: D
authors.lastname: Lugassy
mesh_terms: D000931:Antidotes / Q000494:pharmacology*; D002263:Carboxyhemoglobin / Q000032:analysis* / Q000737:chemistry; D003486:Cyanides / Q000506:poisoning; D003951:Diagnostic Errors / Q000517:prevention & control; D006801:Humans; D006879:Hydroxocobalamin / Q000494:pharmacology*; D009994:Osmolar Concentration; D010092:Oximetry; D011041:Poisoning / Q000097:blood / Q000175:diagnosis; D015203:Reproducibility of Results; D014803:Vitamin B Complex / Q000494:pharmacology*
chemical_list: D000931:Antidotes; D003486:Cyanides; D014803:Vitamin B Complex; D002263:Carboxyhemoglobin; D006879:Hydroxocobalamin
keywords: Carboxyhemoglobin; Hydroxocobalamin; Interference; Laboratory