Clinical Information

Pernicious anemia (PA) is a common form of cobalamin (vitamin B12) deficiency anemia.(1) The disorder is characterized by abnormally large (megaloblastic) red blood cells and atrophic body gastritis (ABG) resulting from autoimmune-mediated destruction of parietal cells that line the stomach wall. The destruction of parietal cells leads to impaired production of intrinsic factor (IF) required for the absorption of vitamin B12. PA is frequently associated with other autoimmune conditions, such as autoimmune thyroid disease, type 1 diabetes mellitus, and vitiligo.(2-5) Diagnosis of PA relies on histologically proven ABG, peripheral blood examination showing megaloblastic anemia, vitamin B12 deficiency, parietal cell antibodies (PCA) with or without intrinsic factor antibodies (IFA), and elevated serum gastrin from loss of acid secretion.(2-4) PCA bind to the alpha- and beta-subunits of the membrane-bound H(+)/K(+)-ATPase while IFA bind directly to intrinsic factor, blocking its ability to bind vitamin B12.(1,4) Both PCA and IFA are useful diagnostic tests for PA, however, compared to PCA, IFA are more specific and lack diagnostic sensitivity.(2,4,5)