Idiopathic aplastic anemia is failure of the bone marrow to properly make all types of blood cells for an unknown reason. The bone marrow is the soft tissue inside bones that helps form blood cells.

See also:

• Anemia
• Secondary (acquired) aplastic anemia

Aplastic anemia results from injury to the blood stem cell, a cell that develops into other blood cell types. The injury causes a reduction in the number of every type of blood cell in the body -- red cells, white cells, and platelets. This reduction is called pancytopenia.

Idiopathic means the cause is unknown. However, idiopathic aplastic anemia is thought to occur when the body reacts against it's own cells. This is called an autoimmune disorder.

The disease may be acute or chronic, and may be slowly get worse. There are no known risk factors.

Aplastic anemia may also be caused by certain medical conditions (such as pregnancy or lupus) or exposure to some toxins or drugs (including chemotherapy). See: Secondary (acquired) aplastic anemia

In some cases, aplastic anemia is associated with another blood disorder called paroxysmal nocturnal hemaglobinuria (PNH).

Symptoms are the result of bone marrow failure and the loss of blood cell production.

Low red cell count (anemia) leads to fatigue and weakness.

Low white cell count (leukopenia) causes an increased risk of infection.

Low platelet count (thrombocytopenia) results in bleeding, especially of mucus membranes and skin.

General symptoms include:

• Bleeding gums
• Easy bruising
• Fatigue
• Frequent or severe infections
• Nose bleeds
• Pallor
• Prolonged bleeding
• Rapid heart rate
• Shortness of breath with exercise
• Swollen lymph nodes (rare)

• Low red blood cells count (anemia)
• Low white blood cell count
• Low reticulocyte count (reticulocytes are immature red blood cell)
• Low platelet count
• Bone marrow biopsy shows few blood cells

Mild cases of aplastic anemia may be treated with supportive care or may require no treatment.

In moderate cases, blood transfusions and platelet transfusions will help correct the abnormal blood counts and relieve some symptoms.

Severe aplastic anemia, which shows up as a very low blood-cell count, is a life-threatening condition. Bone marrow transplant is recommended for severe disease in younger patients.

For older patients, or for those who do not have a matched bone marrow donor, horse antithymocyte globulin (Atgam) or rabbit antithymocyte globulin (thymoglobulin) are alternative treatments. These medicines suppress the body's immune system, allowing the bone marrow to once again make blood cells. Atgam may be used with another drug, such as cyclosporine.

Other medications to suppress the immune system, such as cyclophosphamide (Cytoxan) or corticosteroids, may be also used.

Untreated aplastic anemia is an illness that leads to rapid death. Bone marrow transplant has been successful in young people, with long term survival of 80%. Older people have a survival rate of 40 - 70%.

• Severe infections or bleeding
• Complications of bone marrow transplant (graft failure or graft-versus-host disease)
• Reactions to medications (patients can have reactions to Atgam)

Call your health care provider or go to the emergency room if bleeding occurs for no reason, or if bleeding is difficult to stop. Call if you notice frequent infections or unusual fatigue.

There is no known prevention for idiopathic aplastic anemia.

Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: pp.1241-6.