A viral trigger for a metabolic crisis: parainfluenza induced decompensation in a child with glycogen storage disease type III and complex congenital heart disease

Glycogen storage disease type III (GSD III) also known as Cori’s disease is a rare autosomal recessive metabolic disorder caused by the deficiency of glycogen debranching enzyme (amylo-1,6-glucosidase), leading to hepatomegaly, hypoglycemia, ketosis, and variable cardiac involvement. Intercurrent infections may precipitate metabolic decompensation, particularly in young children. This case report describes a 21-month-old baby boy, known case of GSD III with complex congenital heart disease who presented with fever and respiratory symptoms secondary to parainfluenza infection, complicated by metabolic acidosis, ketosis, electrolyte imbalance and liver enzyme derangement. Prompt recognition and early initiation of dextrose containing fluids prevented further deterioration. This case highlights the importance of early metabolic support during acute illness in children with GSD III, especially in those with coexisting cardiac disease.