| Disorder | Examples | Basic pathophysiology | Blood gas | Ammonia | Glucose | Ketones | Lactate |
|---|---|---|---|---|---|---|---|
| Urea cycle disorders | OTC deficiency | Defect in breakdown of nitrogen → ammonia | Respiratory alkalosis/normal | ↑↑↑ | - | - | - |
| Amino acid disorders | PKU, MSUD, homocystinuria | Defect in breakdown of amino acids | Metabolic acidosis (↑ anion gap) | ↑/- | ↓ | ↑ (MSUD ↑↑↑ urinary ketones) | - |
| Organic acid disorders | Propionic, MMA | Accumulation of organic acids | Metabolic acidosis (↑ anion gap) | ↑ | ↓ | ↑ | ↑ |
| Lysosomal storage disorders | MPS, Pompe, Gaucher, Niemann-Pick | Accumulation of proteins/lipids | - | - | - | - | - |
| Glycogen storage disorders | GSD types I-IX | Defect in glycogen synthesis | Metabolic acidosis | - | ↓ | ↑ | ↑ |
| Fatty acid oxidation disorders | MCADD, LCADD, VLCADD | Unable to break down fatty acids → ketones | Metabolic acidosis (↑ acidosis) | - | ↓ | ↓ | -/↑ |
| Mitochondrial disorders | MELAS | Insufficient acetyl coA for Krebs cycle → ↓ ATP | Metabolic acidosis | - | -/↑ | - | ↑↑ |
| Peroxisomal disorders | XL, ADL, Refsum, Zellweger | ↓ metabolism of VLCFA, ↓ bile synthesis | - | - | - | - | - |
References
