Acute metabolic decompensation: recognition and stabilisation

Overview & Definition

Picture a previously well neonate who feeds poorly, vomits, and becomes progressively lethargic over hours to days, with biochemistry that no infection can explain. That arc is the signature of acute metabolic decompensation — a life-threatening biochemical collapse that occurs when an inherited metabolic disorder (IMD) is unmasked by a catabolic stress such as fasting, fever, or surgery.[2] The crisis is biochemical, not infectious, and the child deteriorates because a blocked enzyme pathway floods the body with toxic intermediates while starving it of energy.[2]

Clinically the presentation is dominated by a metabolically toxic brain: encephalopathy, seizures, vomiting, hypotonia, and apnoea. The laboratory fingerprint is one or more of a high anion-gap metabolic acidosis, hyperammonaemia, hypoketotic hypoglycaemia, or lactic acidosis.[6] Recognition is pattern-based and stabilisation is time-critical, because the depth and duration of biochemical derangement — especially the height of ammonia — directly predicts neurological outcome.[5]

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1. [1]Summar ML, Mew NA Inborn Errors of Metabolism with Hyperammonemia: Urea Cycle Defects and Related Disorders Pediatr Clin North Am, 2018.PMID 29502911
2. [2]Wajner M Neurological manifestations of organic acidurias Nat Rev Neurol, 2019.PMID 30914790
3. [3]Yıldız Y, Akcan Yıldız L, Dursun A, et al. Predictors of acute metabolic decompensation in children with maple syrup urine disease at the emergency department Eur J Pediatr, 2020.PMID 32048023
4. [4]Raina R, Bedoyan JK, Lichter-Konecki U, et al Consensus guidelines for management of hyperammonaemia in paediatric patients receiving continuous kidney replacement therapy Nat Rev Nephrol, 2020.PMID 32269302
5. [5]Hediger N, Landolt MA, Diez-Fernandez C, et al The impact of ammonia levels and dialysis on outcome in 202 patients with neonatal onset urea cycle disorders J Inherit Metab Dis, 2018.PMID 29520739
6. [6]Eiroa H, Durand C, Szlago M, et al Initial management of acute hyperammonemia in pediatrics Arch Argent Pediatr, 2023.PMID 36287611
7. [7]Chapman KA, Ah Mew N, Mickle N, et al Propionic acidemia and methylmalonic aciduria: A portrait of the first 3 years-Admissions and complications Mol Genet Metab, 2025.PMID 41232196
8. [8]Pillai NR, Stroup BM, Poliner A, et al Liver transplantation in propionic and methylmalonic acidemia: A single center study with literature review Mol Genet Metab, 2019.PMID 31757659
9. [9]Mason E, Hindmarch CCT, Dunham-Snary KJ Medium-chain Acyl-CoA dehydrogenase deficiency: Pathogenesis, diagnosis, and treatment Endocrinol Diabetes Metab, 2023.PMID 36300606
10. [10]Servais A, Abi-Wardé MT, Arnoux JB, et al. Management of acute metabolic decompensation in maple syrup urine disease: guidance based on international clinical practice Orphanet J Rare Dis, 2026.PMID 42251408
11. [11]Jagadisan B, Dhawan A Emergencies in paediatric hepatology J Hepatol, 2022.PMID 34990749
12. [12]Van Gosen L Organic acidemias: a methylmalonic and propionic focus J Pediatr Nurs, 2008.PMID 18492552