Nutrition and Oral Medicine (Nutrition and Health)

Chapter 14 / Autoimmune Diseases 243Table 2Selected Systemic Therapies for Autoimmune DisordersCommon indicationsDrug Class PA PV BMMP SLE SS RAPrednisone Glucocorticoid 1 1 2 3 2Mycophenolate mofentil Immunosupp 1 2 2 3 3Azathioprine Immunosupp 2 2 2 3 3Dapsone Antileprosy/Disease modifying 2 1 2 3 2Cyclophosphamide Alkylating agent 2 2 2 3Cyclosporin Immunosupp 2 2 2 2Methotrexate Immunosupp; Antimetabolite 2 2 2 2Gold Disease modifying 4 3 3 3 2NSAIDs Anti inflammatory 4 3 1 2 1IVIg n/a 2 3 4Hydroxychloroqine Antimalarial 3 2 2Plasmapheresis n/a 3 3 3Topical, injectable therapies Immunosupp 2 1 2 2Replacement therapy (B 12 ) 1 3Palliative therapy 1 3(e.g., artificial tears,sialagogue, analgesic)1, first-line therapy; 2, second- or third-line therapy or in combination with 1; 3, on rare occasions; 4, notapplicable.3.1. Pernicious Anemia3.1.1. PATHOGENESISAnemia is a decrease in oxygen-carrying capacity of red blood cells (RBC) and canresult from RBC destruction, inadequate RBC production, or blood loss (1,2). PA resultsfrom B 12 (cobalamine) deficiency, most often caused by absorption deficiency ratherthan dietary deficiency (1–3). Cobalamine is an essential compound in folate metabolism,and a lack of either folate or cobalamine results in a defect in DNA synthesis andthe associated megaloblastic changes in cells with relatively high turnover such ashematopoietic precursors and gastrointestinal (GI) epithelium. Cytoplasmic developmentproceeds normally while cell division is slowed, resulting in large cells with anincreased ratio of RNA to DNA. Megaloblastic anemia is certain when the mean corpuscularvolume exceeds 100 fL. Other conditions that can lead to cobalamine deficiencyand megaloblastic anemia include gastrectomy, small-intestine bacterial overgrowth,diverticulosis, scleroderma, tapeworm, tropical sprue, alcoholism, and medications suchas neomycin and colchicine.Cobalamine cannot be synthesized, and dietary sources are limited to animal proteinfoods (meat, fish, poultry, eggs, and dairy), although many enriched and fortified grainproducts have added B 12 (4). With a recommended daily allowance of only 2.5 µg anda storage of approx 4 mg in various body compartments, the onset of symptoms ofanemia usually occurs after several years of inadequate consumption or absorption.