Neurodevelopmental outcome is highly influenced by the duration of the coma and the peak of hyperammonemia highlighting the need for a rapid diagnosis and management of the patient.

Management of acute decompensation in emergency (prevent catabolism and enhance anabolism)

  • Rehydration
  • Stop all protein intake for 24-48 h (protein have to be reintroduce progressively after)
  • Start intravenous glucose (up to 4 to 10 mg/kg/min depending on age) together with electrolytes in isotonic solutions. Insulin is sometimes added

Specific treatment to be considered depending on the patient status

  • Treatment of hyperammonemia (benzoate sodium +/- N-acetylglutamate)
  • Vitamine B12 (if responsive 1 mg/day IM)
  • L-carnitne (50 to 100 mg/kg/d)
  • Treatment of the trigger to avoid catabolism (infection…)

Sampled blood/urine for monitoring the MMA levels.

Long-term management
The treatment relies mainly on a life-long protein restricted diet to lessen the toxic metabolites in association with a high caloric intake to promote anabolism. Natural protein needs to be carefully titrated to allow for normal growth, while avoiding an excessive propiogenic amino acid load. Adjustment protein intake, based on clinical and laboratory findings, is needed throughout life for these patients. Hydroxocobalamin, carntine and antibiotics are often associated to control MMA levels.