Inborn Errors of Metabolism · USMLE Step 1

Which inborn error of metabolism would you suspect in a child with intermittent hypoketotic hypoglycemia, especially during fasting or illness?

  1. Glycogen storage disease type I (von Gierke)
  2. Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency
  3. Phenylketonuria (PKU) due to PAH deficiency
  4. Maple Syrup Urine Disease (MSUD) of branched-chain amino acids
Show answer and explanation

Correct answer: Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

MCAD deficiency impairs fatty acid β-oxidation; during fasting, the inability to oxidize fatty acids prevents ketone production, causing hypoketotic hypoglycemia, often with lethargy or seizures.

Difficulty: Medium Question 15 of 19

Practice all 19 Inborn Errors of Metabolism questions

Keep practicing

More Inborn Errors of Metabolism questions