Management of Fatty Acid Oxidation Defects During Acute Illness
Continuous intravenous glucose infusion is the most effective measure to prevent metabolic decompensation in children with fatty acid oxidation defects during illness episodes. 1
Why Continuous Glucose Infusion is Critical
Children with fatty acid oxidation defects cannot properly metabolize fatty acids for energy during periods of metabolic stress, placing them at high risk for hypoketotic hypoglycemia, hepatic dysfunction, cardiomyopathy, rhabdomyolysis, and Reye-like syndrome during viral illnesses. 1, 2 The pathophysiology is straightforward: these patients lack the enzymatic machinery to convert fatty acids into usable energy substrates, making them entirely dependent on glucose as their primary fuel source during times of increased metabolic demand. 2, 3
Evidence-Based Acute Management Protocol
The American Association for the Study of Liver Diseases explicitly recommends intravenous glucose infusion of at least 10 mg/kg/min to maintain serum glucose above 100 mg/dL during a crisis as first-line therapy. 4, 1 This is not a suggestion—it is the definitive standard of care. 1
Specific Implementation Steps:
- Initiate IV glucose at ≥10 mg/kg/min immediately when illness begins, without waiting for laboratory confirmation or attempting oral intake first. 1
- Maintain serum glucose >100 mg/dL throughout the entire illness episode, monitoring frequently to ensure adequate energy supply. 4, 1
- Do not delay glucose administration during acute illness—early aggressive treatment with IV glucose can reverse symptoms and prevent progression to fulminant liver failure. 1
Why the Other Options Are Wrong
Option B (Fasting to promote ketone production) is dangerous and contraindicated. 1, 5 These patients have hypoketotic hypoglycemia precisely because they cannot generate ketones from fatty acid oxidation—fasting would precipitate metabolic crisis, not prevent it. 2, 6
Option C (High-fat diet) is contraindicated during acute illness. 5 While long-chain fatty acid oxidation defects may require baseline fat restriction with medium-chain triglyceride supplementation (10-25% of total energy), 5 during acute illness the priority is glucose provision, not dietary fat manipulation. The patient cannot oxidize fatty acids regardless of chain length during metabolic stress. 2, 3
Option D (Protein restriction) has no role in fatty acid oxidation defects. 5 Protein restriction is relevant for urea cycle defects and organic acidemias, not for disorders of fatty acid metabolism. 5
Critical Pitfalls to Avoid
- Never allow elective fasting for procedures without IV glucose support—prolonged fasting can precipitate metabolic crisis even in stable patients. 1
- Recognize that dietary management alone is insufficient during acute illness—intravenous glucose is required regardless of oral intake attempts. 1, 5
- Parents must be educated to seek immediate medical attention during any illness—home management with increased oral carbohydrates is inadequate for preventing decompensation. 5
Prognosis with Appropriate Management
Prompt glucose intervention can reverse symptoms, including those associated with acute liver failure, and preclude the need for liver transplantation. 4, 1 The key is aggressive, early treatment with continuous IV glucose at the recommended rate. 1, 7 A recent case report demonstrated successful perioperative management of a child with medium-chain acyl-CoA dehydrogenase deficiency using continuous glucose infusion, with no metabolic decompensation observed. 7
Long-Term Prevention Strategy
Between illness episodes, management focuses on preventing fasting through frequent feedings and uncooked cornstarch supplementation. 5 However, during acute illness, these measures must be replaced with continuous IV glucose infusion—this is non-negotiable. 1, 5