title: False elevation of carboxyhemoglobin: case report.
abstract: BACKGROUND
  Carbon monoxide toxicity in infants and children, like adults, produce nonspecific symptoms with normal vital signs necessitating the serum measurement of carboxyhemoglobin (COHb). In infants, the COHb may be falsely elevated.
  
  
  OBJECTIVE
  Our goal was to report a case of suspected carbon monoxide toxicity in an infant and the likely cause of the falsely elevated serum COHb.
  
  
  METHODS
  A previously healthy 3-month-old girl presented to the pediatric emergency department (ED) with smoke inhalation from a defective furnace. She was asymptomatic. On examination, she was alert, with Glasgow Coma Scale of 15 and normal vital signs. Cardiorespiratory and neurological examinations were completely normal. Because of concern regarding carbon monoxide poisoning, she was treated with normobaric oxygen therapy. Initial and subsequent serum COHb levels were persistently elevated, despite treatment and the infant appearing clinically well. As such, she had a prolonged stay in the ED. Further investigations found that fetal hemoglobin interferes with the spectrophotometric method used to analyze serum COHb levels.
  
  
  CONCLUSIONS
  Carboxyhemoglobin serum level, in infants, may be falsely elevated due to the fetal hemoglobin interfering with standard methods of analysis. Knowledge of the false elevation using standard spectrophotometric methods of COHb in clinically well-appearing infants can decrease unnecessary oxygen therapy and monitoring time in the ED.
authors.affiliation: Division of Emergency Medicine, Children's Hospital at London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Shruti
authors.initials: S
authors.lastname: Mehrotra
authors.forename: Marcia
authors.initials: M
authors.lastname: Edmonds
authors.forename: Rodrick K
authors.initials: RK
authors.lastname: Lim
mesh_terms: D002249:Carbon Monoxide Poisoning / Q000097:blood / Q000175:diagnosis* / Q000628:therapy; D002263:Carboxyhemoglobin / Q000032:analysis*; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital; D005189:False Positive Reactions; D005260:Female; D005319:Fetal Hemoglobin / Q000032:analysis*; D006801:Humans; D007223:Infant; D010102:Oxygen Inhalation Therapy; D018570:Risk Assessment; D015208:Smoke Inhalation Injury / Q000097:blood / Q000175:diagnosis* / Q000628:therapy; D013053:Spectrophotometry
chemical_list: D005319:Fetal Hemoglobin; D002263:Carboxyhemoglobin