Aplastic anemia

Aplastic anemia (AA) is a severe hematologic condition in which the body fails to make blood cells in sufficient numbers. Normally, blood cells are produced in the bone marrow by stem cells that reside there, but patients with aplastic anemia have a deficiency of all blood cell types: red blood cells, white blood cells, and platelets. It occurs most frequently in people in their teens and twenties but is also common among the elderly. It can be caused by immune disease, inherited diseases, or by exposure to chemicals, drugs, or radiation. However, in about half of cases, the cause is unknown. Aplastic anemia can be definitively diagnosed by bone marrow biopsy. Normal bone marrow has 30–70% blood stem cells, but in aplastic anemia, these cells are mostly gone and are replaced by fat. First-line treatment for aplastic anemia consists of immunosuppressive drugs—typically either anti-lymphocyte globulin or anti-thymocyte globulin—combined with corticosteroids, chemotherapy, and ciclosporin. Hematopoietic stem cell transplantation is also used, especially for patients under 30 years of age with a related, matched marrow donor.