A blood disease is a disease which affects the blood. Many blood diseases are congenital, the result of inherited genetic disorders. Others may be acquired, typically in response to some sort of stress in the body. These disorders are distinct from blood-borne diseases, diseases which are carried in the blood. One of the key differences between a blood disease and a blood-borne disease is that blood diseases are not contagious.
There are four types of blood disease. Coagulopathies are disorders which concern bleeding and clotting, such as hemophilia. Anemias concern the lack of hemoglobin, a substance in red blood cells which is vitally necessary for oxygen transport. Hematological malignancies like leukemia are cancers which affect the blood and bone marrow, while hemoglobinopathies are diseases which have to do with the structure of red blood cells. Sickle cell anemia is a classic example of a hemoglobinopathy.
In the case of a disease caused by genetics, the treatment for the disease is usually focused on managing the symptoms to keep the patient comfortable and help him or her lead a normal life. In hemophilia, for example, the patient is provided with clotting factors so that the blood clots normally. These diseases cannot be cured, but they can often be managed very effectively. With the use of gene therapy in the future, it may be possible to address the underlying cause of such disorders.
Blood diseases with external causes such as disease leading to anemia can be treated by addressing the cause, which also clears up the disease. In the case of blood malignancies, the blood may be treated with chemotherapy and radiation to kill the malignant cells, with more extreme procedures like marrow transplants and blood infusions being used in particularly aggressive cases.
Many blood disorders are identified early, because the symptoms can be very debilitating for the patient. In the case of genetic diseases, people who know that their children are at risk may request testing shortly after birth to see if the genetic disorder is present, and some parents use genetic testing in assisted reproduction to select embryos which are free of the genetic disorder. In other instances, people go to the doctor for symptoms like fatigue, pale gums, excessive bleeding or clotting, joint pain, and so forth, and the disease is diagnosed with the assistance of medical tests.