Anemia

Anemia (U.S. spelling) or anaemia is not having enough red blood cells or hemoglobin in the blood.

Blood film with iron deficiency anemia.

Sickle cell anemia. Normal red blood cells are shown in Figure 1; with sickle cell anemia, red blood cells look like figure 2

Types or causes of anemia

Microcytic anemia

• Iron deficiency anemia is the most common type of anemia overall
• Hemoglobinopathies—much rarer
  • Sickle-cell disease (once called sickle-cell anemia)
  • Thalassemia

Normocytic anemia

• Acute blood loss
• Anemia of chronic disease
• Aplastic anemia (bone marrow failure)

Macrocytic anemia

• Megaloblastic anemia due to not having enough of either vitamin B12 or folic acid (or both)
• Pernicious anemia is an autoimmune problem with the parietal cells of the stomach
• Alcoholism
• Methotrexate, zidovudine, and other drugs that stop DNA replication. This is the most common cause in nonalcoholic patients.

Dimorphic anemia

Dimorphic anemia means two types of anemia at the same time. For example, macrocytic hypochromic, due to hookworm infestation leading to not enough of both iron and vitamin B12 or folic acid or following a blood transfusion.