Hypoglycemia | Postprandial | Glycogen storage diseases, hereditary fructose intolerance, galactosemia |
| Fasting, without ketosis | FAODs |
| | HMG-CoA lyase deficiency |
| Fasting, with significant ketosis | Ketotic hypoglycemia, ketone body utilization defects |
Hyperammonemia | Metabolic acidosis (hyperammonemia is secondary in these conditions) | Organic acidemias (propionic acidemia, methylmalonic acidemia, isovaleric acidemia), severe mitochondrial defects |
| Neonatal or episodic | Urea-cycle defects, severe FAODs |
Metabolic acidosis | Altered mental status, maple syrup smell to urine and cerumen, ketonuria | Maple syrup urine disease (note: acidosis may not always be present) |
| Hyperammonemia | Organic acidemias (propionic acidemia, methylmalonic acidemia, isovaleric acidemia) |
Lactic acidosis | Other organ system pathology, childhood onset (ophthalmoplegia, neutropenia, etc.) | Electron transport chain defects (mitochondrial disease) |
| Neonatal lactic acidosis, may have hypotonia, IUGR, respiratory failure | Electron transport chain defects, pyruvate dehydrogenase deficiency, pyruvate carboxylase deficiency |
| Seizures, developmental delay, hypotonia | Pyruvate dehydrogenase deficiency, pyruvate carboxylase deficiency |
Epileptic encephalopathy | Neonatal | Molybdenum cofactor deficiency, pyridoxine responsive seizures, glycine encephalopathy |
Failure to thrive | Vomiting after high-protein meal | Urea-cycle defect, organic acidemias |
| Vomiting after fructose-containing foods | Hereditary fructose intolerance |
| Diarrhea, abdominal distension | Lysosomal acid lipase deficiency (Wolman disease), congenital disorders of glycosylation (MPI-CDG), Fanconi–Bickel syndrome |
| History of hyperbilirubinemia, hearing loss, dysmorphic features | Peroxisomal disorders |
Liver Symptoms | Neonatal onset liver failure | Galactosemia, hereditary tyrosinemia type 1, mitochondrial depletion syndromes, transaldolase deficiency, congenital disorders of glycosylation |
| Neonatal cholestasis | Galactosemia, tyrosinemia type 1, Niemann–Pick disease type C, citrin deficiency, peroxisomal biogenesis defects |
| Liver failure at time of introduction of fructose-containing foods | Hereditary fructose intolerance |
| Late infantile or childhood onset liver failure | GSD type 4, transaldolase deficiency |
| Hepatomegaly or hepatosplenomegaly with or without other organ system symptoms (skeletal abnormalities, bone pain, neurological deterioration) | Lysosomal storage ... |