Profound metabolic acidosis and oxoprolinuria in an adult

J Med Toxicol. 2007 Sep;3(3):119-24. doi: 10.1007/BF03160921.


Introduction: Profound metabolic acidosis in critically ill adults sometimes remains unexplained despite extensive evaluation.

Case report: A 58-year-old female presented in a confused state to the emergency department; she had been confused for several days. Laboratory evaluation revealed a high anion gap metabolic acidosis and modestly elevated acetaminophen level. Lactic acid was only modestly elevated. There was no evidence of ketoacids, salicylate, methanol, or ethylene glycol. A urine sample submitted on day 1 of hospitalization revealed a markedly elevated level of 5-oxoproline.

Discussion: Originally described in children with an inherited defect of glutathione synthetase, 5-oxoproline is an unusual cause of metabolic acidosis. More recently this disturbance has been recognized in critically ill adults without a recognized inherited metabolic disorder. In most of these cases there has been the concomitant use of acetaminophen. Any causal relationship between acetaminophen and this disturbance is speculative.

Conclusion: In critically ill adults with unexplained metabolic acidosis, 5-Oxoproline should be considered in the differential.

Publication types

  • Case Reports

MeSH terms

  • Acetaminophen / adverse effects*
  • Acidosis / etiology*
  • Acidosis / urine
  • Analgesics, Non-Narcotic / adverse effects*
  • Critical Illness / therapy*
  • Female
  • Humans
  • Metabolic Diseases / chemically induced
  • Metabolic Diseases / diagnosis*
  • Metabolic Diseases / etiology
  • Metabolic Diseases / urine
  • Middle Aged
  • Pyrrolidonecarboxylic Acid / urine*


  • Analgesics, Non-Narcotic
  • Acetaminophen
  • Pyrrolidonecarboxylic Acid