Anemia is characterized by a reduction in red blood cell count or hemoglobin levels. Histological examination of blood smears and bone marrow biopsies can reveal critical details. For instance, in iron-deficiency anemia, red blood cells appear microcytic (smaller than normal) and hypochromic (paler than normal). In megaloblastic anemia, caused by vitamin B12 or folate deficiency, red blood cells are macrocytic (larger than normal) and exhibit abnormal nuclear maturation.
