Anemia develops when the number of red blood cells in the bloodstream is reduced. Red blood cells carry oxygen throughout the body.
There are many different causes and types of anemia. Anemia may result from blood loss, the destruction of red blood cells within the body, or the inability of the body to produce enough red blood cells. The type of anemia depends on its cause. For instance, a severe injury that causes bleeding externally or internally can result in blood loss that causes anemia.