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Table 4 Bedside differential diagnostics of inborn errors of metabolism presenting with acute encephalopathy (modified from Haeberle et al.[14])

From: Proposed guidelines for the diagnosis and management of methylmalonic and propionic acidemia

Parameter Condition
UCD MMA/PA β-Keto-thiolase deficiency MSUD β-oxidation defects HMG CoA lyase deficiency HIHA Mitochondrial/PC deficiencye PDH deficiency
↑ NH3 ++ + +/– + + +/–
Acidosis +/– + ++ +/– + + +
Ketonuriaa ++/+++ +++ +/++ +/++
Hypoglycemiab +/– + + ++ +/–
↑ Lactic acidc + + +/– + - ++ ++
↑ AST & ALT (+) +/– ++ +/– +/–
↑ CPK ++ +/–
↑ Uric acid + + + + + +/– +/–
↑ WBC/RBC/Plt + +/–
Weight loss +d + +/– +
  1. Non-standard abbreviations include: MSUD, maple syrup urine disease; HMG-CoA lyase, 3-hydroxy-3-methlyglutaryl-CoA lyase; HIHA, Hyperinsulinism-hyperammonemia syndrome; PC, pyruvate carboxylase; PDH, pyruvate dehydrogenase.
  2. aKetonuria (++ - +++) suggests OA in neonates.
  3. bHypoglycemia and hyperammonemia ("pseudo-Reye") are predominant in 3-HMG-CoA-lyase deficiency (more than in PC deficiency).
  4. cLactic acid elevation refers to a plasma lactate > 6 mmol/l; lower levels of 2-6 mM may be due to violent crying or extensive muscle activity.
  5. dOnly in neonates.
  6. eOnly type B associated with hyperammonemia but not types A and C.
  7. Grade of recommendation: D.