A protein secreted by gastric parietal cells, binds vitamin B12and facilitates its absorption in the terminal ileum.
In pernicious anemia, autoantibodies against gastric parietal cells and intrinsic factor cause parietal cell loss and decrease intrinsic factor production, resulting in poor vitamin B 12 absorption.
The intrinsic factor antibody test confirms the diagnosis of pernicious anemia in only 50% of cases.