Diagnosaurus
Vitamin B12 deficiency
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)
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Last updated: December 1, 2014
Citation
Zeiger, Roni F.. "Vitamin B12 Deficiency." Diagnosaurus, 4th ed., McGraw-Hill Education, 2014. Medicine Central, im.unboundmedicine.com/medicine/view/Diagnosaurus/114646/all/Vitamin_B12_deficiency.
Zeiger RFR. Vitamin B12 deficiency. Diagnosaurus. McGraw-Hill Education; 2014. https://im.unboundmedicine.com/medicine/view/Diagnosaurus/114646/all/Vitamin_B12_deficiency. Accessed July 19, 2025.
Zeiger, R. F. (2014). Vitamin B12 deficiency. In Diagnosaurus (4th ed.). McGraw-Hill Education. https://im.unboundmedicine.com/medicine/view/Diagnosaurus/114646/all/Vitamin_B12_deficiency
Zeiger RFR. Vitamin B12 Deficiency [Internet]. In: Diagnosaurus. McGraw-Hill Education; 2014. [cited 2025 July 19]. Available from: https://im.unboundmedicine.com/medicine/view/Diagnosaurus/114646/all/Vitamin_B12_deficiency.
* Article titles in AMA citation format should be in sentence-case
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T1 - Vitamin B12 deficiency
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A1 - Zeiger,Roni F,
Y1 - 2014/12/01/
BT - Diagnosaurus
UR - https://im.unboundmedicine.com/medicine/view/Diagnosaurus/114646/all/Vitamin_B12_deficiency
PB - McGraw-Hill Education
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DB - Medicine Central
DP - Unbound Medicine
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