A blood disorder caused by a lack of vitamin B12.
Patients who have this disorder do not produce the substance in the stomach that allows the body to absorb vitamin B12. This substance is called intrinsic factor (IF).
Addisonian anemia, also called pernicious anemia (PA), is characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. (Red blood cells, when mature, have no nucleus). It is thus a type of megaloblastic anemia.
Pernicious anemia (PA) was first described (although not by that name) in 1855 by the English physician Thomas Addison. He called it an invariably fatal "idiopathic anemia." The "idiopathic" was a frank admission that the cause of this illness was wholly unknown. The name "pernicious anemia" was coined in 1872 by the German physician Anton Biermer whose description of the disease was superior to that of Addison. The studies of George H. Whipple on the effects of feeding liver in anemia followed by those of George R. Minot and Wm. P. Murphy on the effects of feeding liver specifically in pernicious anemia (PA) led to the cure of PA and to their receiving the Nobel Prize in 1934.
