Treatment often begins with aggressive intervention in an acute metabolic crisis. Hemodialysis, if available, can lower the levels of the branched-chain amino acids and organic acids in the plasma. Generous administration of IV fluids helps eliminate organic acids through renal loss. IV glucose provides an alternate energy source that reduces protein catabolism, which is a major source of branch-chain amino acids in acutely ill infants. Restriction of protein intake is usually a life-long requirement and commercial formulas that are depleted in branched-chain amino acids are available. Carnitine supplementation is useful in removing organic acids and repleting carnitine stores. Some patients respond to high-dose thiamine supplementation, a cofactor of the enzyme complex, and all newly diagnosed critically ill infants should be treated with this vitamin. Close monitoring of patients who survive the newborn period or who have a later presentation is required to reduce morbidity and mortality.
Because the diagnosis and therapy of MSUD is complex, the pediatrician is advised to manage the patient in close collaboration with a consulting pediatric metabolic disease specialist. It is recommended that parents travel with a letter of treatment guidelines from the patient’s physician.