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D-lactic acidosis – SBS — RACP Paediatrics MCQ

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HardGID-lactic acidosis – SBSRACP Paediatrics

A 5-year-old with SBS (post NEC resection, 30 cm residual small bowel with intact ileocaecal valve) develops episodic confusion, ataxia, and slurred speech after high-carbohydrate meals. Blood pH is normal but D-lactate is markedly elevated. What is the diagnosis?

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Correct answer: B — D-lactic acidosis

D-lactic acidosis occurs in SBS when unabsorbed carbohydrates reach the colon and are fermented by bacterial flora to D-lactate (which is not metabolised by human L-lactate dehydrogenase). It presents with encephalopathy (confusion, ataxia, slurred speech) after carbohydrate-rich meals. Standard lactate assays measure L-lactate and may be normal. Treatment includes carbohydrate restriction and oral antibiotics to reduce D-lactate-producing bacteria.

Reference: RACP Paediatric Curriculum – GI/Metabolic; RCH Melbourne – 2023