aetiology
Last reviewed 01/2018
In adults, pernicious anaemia is an auto-immune disorder.
Auto-antibodies to gastric parietal cells are present in 90% of cases but are not pathognomonic as they may occur:
- in other disorders, for example, Addison's disease; iron deficiency anaemia
- in normal relatives of those with PA
- in 16% of randomly selected women over 60 years
Auto-antibodies to intrinsic factor are more specific. They are found in the serum in 55% of cases and in gastric juice in 80%. They are of two types:
- blocking antibody - directed towards the combining site for vitamin B12 on IF
- binding antibody - reacts with an antigenic determinant on IF distinct from the B12 combining site; the reaction may be with free IF or with IF-B12 complex in the terminal ileum to inhibit absorption.
In children pernicious anaemia may occur very rarely due to congenitally absent or abnormal intrinsic factor.