D-lactic acidosis and ataxia in a man with Crohn disease

• Published in: Canadian Medical Association journal (CMAJ) 2010-02, Vol.182 (3), p.276-279
• Main Authors: James, Paul D., MD MSc, Black, David, MD, Kuper, Ayelet, MD DPhil, Saibil, Fred, MD
• Format: Article
• Language: English
• Subjects: Acidosis, Lactic - complications; Acidosis, Lactic - diagnosis; Acidosis, Lactic - metabolism; Anti-Inflammatory Agents - therapeutic use; Antidiarrheals - therapeutic use; Ataxia; Ataxia - complications; Bowel disease; Crohn Disease - complications; Crohn Disease - drug therapy; Crohn's disease; Development and progression; Diagnosis; Diagnosis, Differential; Diet; Health aspects; Humans; Internal Medicine; Intestines - metabolism; Intestines - microbiology; Lactic Acid - metabolism; Lactic acidosis; Loperamide - therapeutic use; Male; Medical diagnosis; Middle Aged; Practice; Prednisone - therapeutic use; Vitamins - therapeutic use
• ISSN: 0820-3946; 1488-2329
• DOI: 10.1503/cmaj.090009

Metabolic acidosis with an elevated anion gap has a limited differential diagnosis (Box 1).1,4-6 The laboratory tests investigating these typical causes were negative in our patient. Dlactic acidosis is a much rarer cause of metabolic acidosis with an elevated anion gap. Its presence is suggested by elevation of the anion gap in patients with shortened small bowels when other causes have been excluded (Table 2). The clinical manifestations of D-lactic acidosis are listed in Box 21,4,10 and include altered mental status and cerebellar ataxia. The cause of these neurologic abnormalities is debated. A reduction in serum pH alone is insufficient to explain such manifestations, given that acidosis of comparable severity from other causes does not always result in this presentation. Various theories have been advanced, including suggestions that low pH may affect intraneural metabolism of L-lactate, which is the preferred substrate of nervous aerobic metabolism,11 or may inhibit central and peripheral neurotransmitter production.4,12 The accumulation of D-lactate in brain tissue because of naturally low levels of Dlactate dehydrogenase has also been hypothesized.11 These theories are not supported by a study showing that infusion of D-lactate into healthy volunteers to a serum concentration of 6 mmol/L did not cause neurologic symptoms.9 This finding suggests the presence of other mediators associated with D-lactate.1,5,9 However, infusing D-lactate into peripheral venous blood may not reproduce the clinical presentation associated with D-lactic acidosis because D-lactate absorbed from the colon passes through the portal circulation and into the liver before being released into the systemic circulation.