Neonatal transition
Diagnosis before the development of encephalopathy Nutritional therapy to correct leucinosis and achieve sustained anabolisma Prevention of hyponatremia and brain herniation Prevention of essential amino acid deficiencies
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Longitudinal metabolic control
Weekly amino acid monitoring; turnaround time 24 h or less Routine monthly outpatient visit to monitor growth, development, and diet Age-specific intake of leucine, calories, total protein, vitamins and micronutrientsb Supplement valine and isoleucine to plasma ratio goals: Leu/Iso = 2 mol:mol; Leu/Val ≥ 0.5 mol:mol Enrich diet with LAT 1 substrates,c alanine, and glutamine Prevent nutrient deficiencies that result from chronic dependence on artificial foods
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Management of episodic catabolic illnesses
Provide access to informed pediatric care during common illnesses, injuries, and surgeries Identify and treat infections or other physiologic stresses that precipitate catabolic illness Stop leucine intake and provide (per kg per day): 120–170 kcal, 2.5–3.0 g protein Increase isoleucine and valine supplements to 15–30 mg/kg each Monitor amino acids every 1–3 days and adjust dietary intake accordingly Give odansetron PO or SL for nausea or vomiting Limit free water intake and carefully monitor for signs of cerebral edema Resume leucine intake when plasma leucine ≤100 μM
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Acute inpatient care
MSUD pareteral solution on demand; enrich TPN with LAT 1 substrates,c,d alanine, and glutamine Enteral feeding (PO or per NG tube) with BCAA-free formula as tolerated Provide 150–200% energy expenditure, lipid 50% non-protein calories, BCAA-free protein 2.5–3.0 g/kg day Dextrose ≥ 10 mg/kg min; insulin infusion titrated to euglycemia (e.g., 0.05–0.15 U/kg h) Isoleucine and valine IV (1% solutions in normal saline), 20–120 mg/kg day each, adjusted based on levels Plasma amino acid testing 1 or 2 times daily; turnaround time 4 h or less Odansetron IV (0.15 mg/kg/dose) every 6–8 h for nausea or vomiting Maintain serum osmolality (290–300 mOsm/kg) and sodium (138–145 mEq/L) within a narrow rangee Monitor for signs of brain edema and increased intracranial pressure Treat hypo-osmolality with furosemide (0.5–1 mg/kg), mannitol (0.5 g/kg), and hypertonic saline (2–3 mEq/kg)f Monitor for pancreatitis
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Goals of long-term therapy
Prevention of death or permanent brain injury during acute metabolic crises Normal growth and neurological development Plasma leucine 50–200 μM on an age-appropriate leucine intake (see Table 4) Plasma isoleucine:leucine ratio approximately 0.5 mol:mol; valine:leucine ratio ≥2 mol:mol Normal long-term plasma concentration ratios of leucine to competing LAT 1 substratesc Plasma alanine 150–500 μM; glutamine 400–800 μM Normal laboratory indices of nutritional sufficiency Normal red blood cell membrane eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid levels
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