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Medium-chain acyl-CoA dehydrogenase deficiency — RACP Paediatrics MCQ

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HardGenetics and metabolicMedium-chain acyl-CoA dehydrogenase deficiencyRACP Paediatrics

A 16-month-old becomes encephalopathic after gastroenteritis with poor intake. Glucose is 1.7 mmol/L, ketones are low and liver enzymes are mildly elevated. Newborn screening overseas was not performed. What is the most likely cause?

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Correct answer: C — Fatty acid oxidation disorder causing hypoketotic hypoglycaemia

Hypoketotic hypoglycaemia during fasting illness suggests a fatty acid oxidation defect such as MCAD deficiency. Diabetic ketoacidosis would cause hyperglycaemia and ketosis, not low glucose with absent ketones. Emergency management focuses on avoiding catabolism and giving glucose.

Reference: Australian newborn bloodspot screening programme; RACP Knowledge Guides