Of rare acid-base disturbances, some are inexplicably favoured by CICM examiners, and other are inexplicably neglected. For some reason pyroglutamic acidosis has been the subject of several SAQs, whereas D-lactic acidosis has never appeared in the exam.

An excellent article on this topic is available. The content below is a brief summary of this article.

Pathophysiology

  • Malabsorbed carbohydrate is fermented by Lactobacillus, Bifidobacterium, Eubacterium and Streptococcus bovis in the colon, producing an excess of D-lactate.
  • This has been a well-recognised problem in ruminants.
  • Normally, humans have a great capacity to metabolise D-lactate (the hepatic metabolism of lactate does not discriminate between isoforms)

Implications for the diagnosis of a high anion gap metabolic acidosis

  • D-lactate is not routinely measured (L-lactate levels look normal)
  • Thus, the patients appear to have a high anion gap metabolic acidosis with a normal lactate

Clinical features

  • Symptoms are neurological: confusion, slurred speech, obtundation and ataxia.
  • Encephalopathy of one sort or another seems to be the most common feature

Risk factors

  • Short gut patients are particularly at risk
  • Post-pancreatectomy patients who fail to take their enzyme supplements
  • Short gut hippies who ingest Lactobacillus tablets to improve their intestinal microflora
  • Symptoms are exacerbated by increased food intake, and are relieved by fasting

References

Uribarri, Jaime, Man S. Oh, and Hugh J. Carroll. "D-lactic acidosis: a review of clinical presentation, biochemical features, and pathophysiologic mechanisms."MEDICINE-BALTIMORE- 77 (1998): 73-82.