Table 4.
Bedside differential diagnostics of inborn errors of metabolism presenting with acute encephalopathy (modified from Haeberle et al. [14])
| Parameter | Condition | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| UCD | MMA/PA | β-Keto-thiolase deficiency | MSUD | β-oxidation defects | HMG CoA lyase deficiency | HIHA | Mitochondrial/PC deficiency e | PDH deficiency | |
| ↑ NH3 | ++ | + | – | – | +/– | + | + | +/– | – |
| Acidosis | +/– | + | ++ | – | +/– | + | – | + | + |
| Ketonuriaa | – | ++/+++ | +++ | +/++ | – | – | – | +/++ | – |
| Hypoglycemiab | – | +/– | – | – | + | + | ++ | +/– | – |
| ↑ Lactic acidc | – | + | + | – | +/– | + | – | ++ | ++ |
| ↑ AST & ALT | (+) | +/– | – | – | ++ | +/– | – | +/– | – |
| ↑ CPK | – | – | – | – | ++ | – | – | +/– | – |
| ↑ Uric acid | – | + | + | + | + | + | – | +/– | +/– |
| ↓ WBC/RBC/Plt | – | + | – | – | – | – | – | +/– | – |
| Weight loss | – | +d | + | +/– | – | – | – | + | – |
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.
aKetonuria (++ - +++) suggests OA in neonates.
bHypoglycemia and hyperammonemia (“pseudo-Reye”) are predominant in 3-HMG-CoA-lyase deficiency (more than in PC deficiency).
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.
dOnly in neonates.
eOnly type B associated with hyperammonemia but not types A and C.
Grade of recommendation: D.