TY - CHAP M1 - Book, Section TI - Megaloblastic Anemias A1 - Hoffbrand, A. Victor A2 - Kasper, Dennis A2 - Fauci, Anthony A2 - Hauser, Stephen A2 - Longo, Dan A2 - Jameson, J. Larry A2 - Loscalzo, Joseph PY - 2014 T2 - Harrison's Principles of Internal Medicine, 19e AB - The megaloblastic anemias are a group of disorders characterized by the presence of distinctive morphologic appearances of the developing red cells in the bone marrow. The marrow is usually hypercellular and the anemia is based on ineffective erythropoiesis. The cause is usually a deficiency of either cobalamin (vitamin B12) or folate, but megaloblastic anemia may occur because of genetic or acquired abnormalities that affect the metabolism of these vitamins or because of defects in DNA synthesis not related to cobalamin or folate (Table 128-1). Cobalamin and folate absorption and metabolism are described next, followed by the biochemical basis, clinical and laboratory features, causes, and treatment of megaloblastic anemia. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2022/08/17 UR - accessmedicine.mhmedical.com/content.aspx?aid=1125225529 ER -