Typical symptoms include malaise, pallor, and dyspnea attributable to anemia. Vitamin B12 deficiency can result in both central and peripheral nervous system manifestations (eg, paresthesias, loss of proprioception, poor concentration, and depression) as well as anosmia and atrophic glossitis. Gastrointestinal symptoms (eg, abdominal pain, diarrhea, and constipation) may be present.
If treated, many of these manifestations are reversible. However, if undiagnosed and untreated, some neurologic manifestations can be permanent. The hallmarks of therapy include vitamin B12 repletion. However, this does not reverse the underlying autoimmune gastritis. If gastrointestinal symptoms develop, patients should be evaluated for gastric cancers given their increased risk.
For more information on Imerslund-Grasbeck syndrome (juvenile pernicious anemia), see OMIM.
For more information on congenital pernicious anemia due to a defect in intrinsic factor, see OMIM.
D51.0 – Vitamin B12 deficiency anemia due to intrinsic factor deficiency
84027009 – Pernicious anemia
- Malnutrition / eating disorder (anorexia, bulimia) with nutritional vitamin B12 deficiency
- Vegan or vegetarian diet with nutritional vitamin B12 deficiency (dairy and meat are primary sources)
- Imerslund-Grasbeck disease
- Gastric cancer
- Celiac disease
- Tropical sprue
- Inflammatory bowel disease (eg, Crohn disease, ulcerative colitis)
- Bariatric surgery
- Iatrogenic: medications that block gastric acid
- Nitrous oxide abuse
- Myelodysplastic syndrome
- Folic acid deficiency
- Small intestinal bacterial overgrowth
- Zollinger-Ellison syndrome
- Gastric outlet obstruction
- Delayed gastric emptying