Overview
Vitamin B12, also known as cobalamin, is an important cofactor in the homocysteine metabolism, haemoglobin synthesis and myelination.
Pathogenesis
Causes of B12 Deficiency
- Atrophic gastritis - pernicious anaemia, H pylori infection
- Malabsorption - coeliac disease, tropical sprue, Crohn's disease, alcohol abuse
- Surgical resection - gastrectomy, gastric bypass, resection of terminal ileum
- Pancreatic insufficiency - chronic pancreatitis
- Inherited disorders - Imerslund-Gräsbeck syndrome
Dietary deficiency is rare as a cause of B12 deficiency.
Manifestations
Manifestations of B12 Deficiency Anaemia
- Megaloblastic anaemia
- Atrophic glossitis
- Peripheral neuropathy
- Dementia
Diagnosis
Investigations
- Reduced Vitamin B12 level
- Macrocytic, hyperchromic anaemia
- Hypersegmented neutrophils
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