Genetics of Methylmalonic Acidemia Treatment & Management

Updated: Mar 15, 2019
  • Author: Brendan Lee, MD, PhD; Chief Editor: Maria Descartes, MD  more...
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Medical Care

Infants and children with methylmalonic acidemia (MMA) are at increased risk for metabolic decompensation particularly during episodes of increased catabolism (eg, intercurrent infections, trauma, surgery, psychosocial stress). During these episodes, provide treatment that is swift and directed towards reversing catabolism and promoting anabolism.

Limit protein catabolism during acute metabolic crises. Stop usual protein intake and intravenously administer generous fluid and glucose (4-8 mg/kg/min, depending on age) if necessary. Cessation of protein intake should last for no longer than 24 hours.

Continue medication and increase carnitine intake to 200-300 mg/kg/d intravenously if necessary.

Provide appropriate treatment of concurrent illnesses (eg, infections).

Provide early reintroduction of protein intake (within 1-2 d after onset of acute decompensation).

N -carbamyl glutamate (100-250 mg/kg/d) orally can be used to treat hyperammonemia.

Consider hemodialysis or hemofiltration for persistent hyperammonemia and/or metabolic acidosis.


Surgical Care

Several liver and kidney transplantations in infants and children with MMA mut0 have been reported.

Despite apparent corrections of the enzyme defect, children with liver or kidney transplantations continue to excrete MMA. Some of these children also develop a movement disorder.

Consider liver transplantation early in infancy to potentially prevent some of the devastating neurological complications.



Patients require a low-protein diet that provides the minimum natural protein required for growth. Increase dietary protein according to age, weight, and (essential) plasma amino acids levels. [20] Plasma MMA levels may be followed for metabolic control.

Metabolic formula deficient in propiogenic amino acids should be used to provide sufficient protein for growth while limiting whole protein sources to minimize MMA levels.

Avoid long fasts. Provide a late night snack and/or early breakfast to limit the duration of overnight fasting.

Provide calcium and multivitamin supplementation to avoid osteopenia and vitamin deficiency, respectively.



Do not restrict activity.