Cardiac arrest in infancy: don't forget glucose!

Area of Science:

• Biochemistry
• Genetics
• Pediatrics

Background:

• Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is an inherited metabolic disorder affecting fatty acid oxidation.
• It can lead to severe hypoglycemia, particularly during periods of metabolic stress like illness or fasting.

Observation:

• A 2-year-old girl presented with collapse, unconsciousness, and bradycardia, requiring cardiopulmonary resuscitation (CPR).
• Initial assessment revealed profound hypoglycemia (<0.5 mmol/l) with minimal ketosis, atypical for typical causes of pediatric arrest.
• Metabolic screening confirmed MCAD deficiency.

Findings:

• Patients with MCAD deficiency exhibit impaired fatty acid oxidation, leading to reliance on glucose.
• This results in severe hypoglycemia and hypoketonuria when glucose stores are depleted, as ketones are not adequately produced.
• Delayed blood glucose checks in pediatric resuscitation can obscure this critical diagnosis.

Implications:

• Prompt recognition and diagnosis of MCAD deficiency are vital for initiating preventative measures.
• Early intervention can avert metabolic decompensation, neurological sequelae, and sudden death, which occurs in 18% of undiagnosed cases.
• This case highlights the importance of considering inborn errors of metabolism in pediatric emergencies presenting with unexplained hypoglycemia.