how pernicious anaemia can be associated with atrophic gastritis - and a combined B12 and iron deficiency
Last edited 04/2020
About 20% of patients with pernicious anaemia have coexisting iron deficiency - blood film may reveal normocytic anaemia, or even microcytic anaemia in extreme circumstances, masking the diagnosis of B12 deficiency (1).
A combined iron deficiency and B12 deficiency scenario may occur because of the combination of pernicious anaemia plus atrophic gastritis
- in pernicious anaemia intrinsic factor antibodies lead a reduction in intrinsic factor and hence reduced absorption of vitamin B12
- in atrophic gastritis antibodies to gastric parietal cells result in parietal cell damage; and hence reduced levels of intrinsic factor. There is also a consequent achlorhydria that reduces the absorption of iron; and decreases the release of dietary bound vitamin B12 - hence contributing to both deficiencies in iron and B12
| Anti-Intrinsic Factor antibodies | Anti-gastric parietal cell antibodies: |
> lead to a reduction in intrinsic factor > causing a reduction in vitamin B12 absorption> causing vitamin B12 deficiency . . . . . . |
parietal cell damage (autoimmune gastritis, atrophic gastritis) results in:
|
Reference:
- Mohamed M et al. Pernicious anaemia. BMJ 2020;369:m1319.
- NHS Wiltshire CCG. Investigation and treatment of Vitamin B12 (cobalamin) deficiency in primary care (accessed 25/4/2020)
- Royal United Hospital Bath NHS Trust. Guidelines for the Investigation & Management of vitamin B12 deficiency (accessed 25/4/2020).