Falsely normal anion gap in severe salicylate poisoning caused by laboratory interference

Ann Emerg Med. 2011 Sep;58(3):280-1. doi: 10.1016/j.annemergmed.2011.02.023. Epub 2011 Apr 14.


Severe salicylate poisoning is classically associated with an anion gap metabolic acidosis. However, high serum salicylate levels can cause false increase of laboratory chloride results on some analyzers. We present 2 cases of life-threatening salicylate poisoning with an apparently normal anion gap caused by an important laboratory interference. These cases highlight that the diagnosis of severe salicylism must be considered in all patients presenting with metabolic acidosis, even in the absence of an increased anion gap.

Publication types

  • Case Reports

MeSH terms

  • Acid-Base Equilibrium / drug effects*
  • Adult
  • Anti-Inflammatory Agents, Non-Steroidal / poisoning*
  • Aspirin / poisoning*
  • Clinical Laboratory Techniques / adverse effects*
  • Clinical Laboratory Techniques / standards
  • Drug Overdose / diagnosis
  • Emergency Service, Hospital
  • False Negative Reactions*
  • Female
  • Humans
  • Male
  • Middle Aged


  • Anti-Inflammatory Agents, Non-Steroidal
  • Aspirin