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MCAD – critical sample pattern — RACP Paediatrics MCQ

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HardEndocrineMCAD – critical sample patternRACP Paediatrics

The critical sample shows: glucose 2.0, insulin suppressed, C-peptide low, ketones suppressed, FFAs elevated, acylcarnitine profile shows elevated C8 (octanoylcarnitine). What is the diagnosis?

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Correct answer: E — Acylcarnitine profile

Hypoketotic hypoglycaemia with suppressed insulin, elevated FFAs (mobilisation is occurring but beta-oxidation is impaired), and elevated C8 acylcarnitine is MCAD deficiency. FFAs are elevated because they cannot be oxidised; ketones are suppressed because ketogenesis requires beta-oxidation. This is the characteristic pattern of fatty acid oxidation defects.

Reference: RCH Melbourne – 2023 – Hypoglycaemia CPG; RACP Paediatric Curriculum – Metabolic