Version July 2025
| Findings | Maple syrup urine disease | Organic acidemias | Urea cycle defects | Disorders of carbohydrate metabolism | Fatty acid oxidation disorders | Mitochondrial disorders | Peroxisomal disorders | Lysosomal storage disorders |
| Metabolic acidosis | ± | ++ | – | ± | ± | ± | – | – |
| Respiratory alkalosis | – | – | + | – | – | – | – | – |
| Hyperammonemia¶ | ± | + | ++ | – | ± | – | – | – |
| Hypoglycemia | ± | ± | – | + | + | ± | – | – |
| Ketones | A/H | H | A | A/H | A/L | A/H | A | A |
| Lactic acidosis | ± | ± | – | + | ± | + | – | – |
–: usually absent; ±: sometimes present; +: usually present; ++: always present; A: appropriate production of ketones for the degree of hypoglycemia (eg, ketones are appropriately absent in peroxisomal disorders because hypoglycemia is not a feature of these disorders); H: inappropriately high (eg, 4+ ketones are inappropriately high in the setting of a normal glucose level); L: inappropriately low (eg, ketones are inappropriately low if the blood glucose is <20 mg/dL and the urine ketones are only 1+ or 2+ because they should be significantly elevated in the setting of such extreme hypoglycemia).
* Within disease categories, not all diseases have all findings; for disorders with episodic decompensation, clinical and laboratory findings may be present only during acute crisis; for progressive disorders, findings may not be present early in the course of disease.
¶ Improper collection, sample mishandling, and delay in analysis can result in spuriously elevated ammonia levels. An ammonia specimen should be obtained from a free-flowing (no tourniquet) venous specimen, the test tube should immediately be placed on ice, and the sample should analyzed within 30 minutes.