Advances in mechanisms, diagnosis, and treatment of pernicious anemia.

Pernicious anemia (PA) is an entity initially described in 1849 as a condition that consisted of pallor, weakness, and progressive health decline. Since then several advances led to the conclusion that PA is an autoimmune disease characterized by the deficient absorption of dietary cobalamin. It is currently recognized as the most common cause of cobalamin deficiency worldwide. We hereby review the current understanding of the disease and its neurological, hematological, and biochemical manifestations with emphasis on the diagnostic approach, treatment, and monitoring strategies. We propose an algorithm for the diagnostic approach considering the current performance and limitations of the available diagnostic tools for evaluation of cobalamin status and the presence of autoimmune chronic atrophic gastritis (CAG). Patients with PA require lifelong treatment with cobalamin replacement therapy. The current widely available treatment can be provided through enteral or parenteral cobalamin supplements, with comparable efficacy and tolerability.