Pernicous Anemia

Pernicious anaemia - Malabsorption of vitamin B12 can occur at several points during digestion. By far the most important condition resulting in vitamin B12 malabsorption is the auto-immune disease called pernicious anaemia (PA). In most cases of PA, antibodies are produced against the parietal cells causing them to atrophy, lose their ability to produce intrinsic factor, and secrete hydrochloric acid. In some forms of PA the parietal cells remain intact but auto-antiobodies are produced against the intrinsic factor itself and attach to it, thus preventing it from binding vitamin B12. In another less common form of PA, the antibodies allow vitamin B12 to bind to the intrinsic factor but prevent the absorption of the intrinsic factor–vitamin B12 complex by the ileal receptors. As is the case with most auto-immune diseases, the incidence of PA increases markedly with age.