The anemia is characterized by a diminution in the concentration of hemoglobin or the capacity to transport oxygen in the blood. In the megaloblastic anemia a red diminution of the number of erythrocytes or globules takes place, and an increase in the size of such due to a deficiency of substances that take part in the eritropoyesis or formation of red globules, as it is the B12 vitamin. Nevertheless, the deficiency of this vitamin is secondary to the lack a protein of the gastric mucosa (intrinsic factor) this one yes basic one for its absorption. In these cases the intrinsic factor takes place and secret in minimum, insufficient amounts to make sure a normal intestinal absorption the vitamin or it does not take place absolutely.