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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.