DDx ⬇
- Folic acid deficiency
- Myelodysplastic syndrome
- Other causes of peripheral neuropathy, ataxia, or dementia
Related DDx ⬆ ⬇
Etiology ⬆
- Dietary deficiency (seen in vegans)
- Decreased intrinsic factor production: pernicious anemia, gastrectomy
- Competition for B12 in gut: blind loop syndrome, fish tapeworm (rare)
- Decreased ileal B12 absorption: surgical resection, Crohn's disease, metformin
- Pancreatic insufficiency
- Helicobacter pylori infection
- Transcobalamin II deficiency (rare)