In short bowel syndrome with small bowel bacterial overgrowth (SBBO), which metabolic complication is most likely to occur?

• A. D-lactic acidosis
• B. D-lactic alkalosis
• C. Metabolic alkalosis
• D. Respiratory acidosis

Answer: (A)

The main concept is that small bowel bacterial overgrowth after extensive resection leads to excessive fermentation of unabsorbed carbohydrates by gut bacteria, producing D-lactate. Humans don’t efficiently metabolize D-lactate, so it accumulates in the blood, causing a metabolic acidosis with an elevated anion gap. Clinically, this can present with neurologic symptoms such as confusion or ataxia after meals.

That’s why D-lactic acidosis is the best answer: it reflects the specific metabolic disturbance from overgrown bacteria producing the D-enantiomer of lactate in the setting of malabsorption.

Metabolic alkalosis and respiratory acidosis don’t fit this scenario. Alkalosis would require bicarbonate gain or hydrogen loss not typical of SBBO, and respiratory acidosis arises from hypoventilation with CO2 retention, not from bacterial overgrowth. D-lactic alkalosis isn’t a recognized clinical entity.