Overview
Maple syrup urine disease (MSUD) is an inherited metabolic disorder characterized by a deficiency in the branched-chain α-keto acid dehydrogenase complex, leading to elevated levels of branched-chain amino acids (BCAAs) and their corresponding keto acids, causing symptoms such as ketoacidosis, poor feeding, neurological deficits, and potential brain damage 2345.Diagnosis
Clinical Presentation: Poor feeding, lethargy, vomiting, dehydration, neurological signs, ketonuria, and ketoaciduria 2.
Laboratory Tests: Elevated levels of BCAAs (leucine, isoleucine, valine) and their keto acids in blood and urine 26.
Key Biomarkers: Uric acid and anion gap are particularly useful markers for acute metabolic decompensation 2.Management
Dietary Management: Dietary restriction of BCAAs with supplementation of essential amino acids excluding BCAAs 34.
L-Carnitine Supplementation: May decrease oxidative stress and DNA damage in MSUD patients 45.
Emergency Care: Prompt recognition and treatment of acute metabolic decompensation are critical; focus on correcting fluid and electrolyte imbalances, managing acidosis, and ensuring adequate nutrition 3.Special Populations
Pediatrics: Early intervention is crucial; uric acid and anion gap are key indicators for acute decompensation 2.
Iatrogenic Complications: Risk of developing acrodermatitis enteropathica-like syndrome due to isoleucine deficiency during treatment with BCAA-free formulas; ensure adequate amino acid supplementation 7.Key Recommendations
Monitor uric acid and anion gap levels to identify acute metabolic decompensation in MSUD patients (Evidence: Moderate 2).
Implement a BCAA-restricted diet supplemented with essential amino acids excluding BCAAs for long-term management (Evidence: Expert opinion 3).
Consider L-carnitine supplementation to mitigate oxidative stress and DNA damage in MSUD patients (Evidence: Moderate 45).
Administer immediate treatment with vitamins, minerals, and trace elements upon diagnosis to potentially reactivate deficient enzymatic systems, especially in neonates (Evidence: Moderate 6).
Avoid iatrogenic deficiencies, particularly in isoleucine, when using BCAA-free formulas to prevent complications like acrodermatitis enteropathica-like syndrome (Evidence: Weak 7).References
1 Treasure T. Pulmonary mischief 1893-1894. Journal of the Royal Society of Medicine 2025. link
2 Yıldız Y, Akcan Yıldız L, Dursun A, Tokatlı A, Coşkun T, Tekşam Ö et al.. Predictors of acute metabolic decompensation in children with maple syrup urine disease at the emergency department. European journal of pediatrics 2020. link
3 Rodan LH, Aldubayan SH, Berry GT, Levy HL. Acute Illness Protocol for Maple Syrup Urine Disease. Pediatric emergency care 2018. link
4 Mescka CP, Guerreiro G, Hammerschmidt T, Faverzani J, de Moura Coelho D, Mandredini V et al.. L-Carnitine supplementation decreases DNA damage in treated MSUD patients. Mutation research 2015. link
5 Mescka CP, Wayhs CA, Guerreiro G, Manfredini V, Dutra-Filho CS, Vargas CR. Prevention of DNA damage by L-carnitine induced by metabolites accumulated in maple syrup urine disease in human peripheral leukocytes in vitro. Gene 2014. link
6 Mogoş T, Cheţa CP, Mincu IT. Clinical consequences of disorders in the intermediate metabolism of branched chain amino acids (valine, leucine and isoleucine). Romanian journal of internal medicine = Revue roumaine de medecine interne 1994. link
7 Giacoia GP, Berry GT. Acrodermatitis enteropathica-like syndrome secondary to isoleucine deficiency during treatment of maple syrup urine disease. American journal of diseases of children (1960) 1993. link