B12 Deficiency

Exam Cram

• B12 absorbed in the terminal ileum, requiring intrinsic factor

• Helps maintains nerves, including spinal dorsal column responsible for vibration, proprioception

• Causes of B12 deficiency: dietary (vegans) or malabsorption (Crohn's, pernicious anaemia)

• Presentation: symptomatic anaemia- lethargy, sob, palpitations; peripheral neuropathy, dorsal column neuropathy 

• Investigations: macrocytic anaemia, low B12

• Management: IM hydroxocobalamin( if malabsorptive) or PO cyanocobalamin replacement 

Outline

Background

Assessment

History

• Lethargy

• Unsteadiness on feet

• Lower limb numbness

Examination

• Dorsal column: loss of proprioception, vibration

• Ataxia

• Upward plantars

Investigations

• Macrocytic Anaemia

• Low B12

Diagnosis

Diagnostic criteria: low serum B12

Differentials: low folate

Classification (aetiology)

• Poor diet - vegan

• Poor absorption / increased losses- Crohn's Disease , Coeliac Disease 

Management

Acute

• IM B12 replacement- 6 doses over two weeks

Long term

• IM B12 injection 3 monthly OR

• PO B12

Med Reg Notes

References and Resources

Created in 2024.