Causes

Aplastic anemia results from injury to the blood stem cells, immature cells in the bone marrow that give rise to all of other blood cells types. The injury causes a decrease in the number of every type of blood cell in the body -- red cells, white cells, and platelets. Low numbers of red cells, white cells, and platelets is a condition called pancytopenia.

Idiopathic means the cause is unknown. However, idiopathic aplastic anemia is thought to occur when the body's immune system mistakenly destroys healthy cells. This is called an autoimmune disorder.

The disease may be acute or chronic, and may get worse over time. 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 hemoglobinuria (PNH).

Symptoms

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

Low red cell count (anemia) can cause:

• Fatigue
• Pallor (paleness)
• Rapid heart rate
• Shortness of breath with exercise
• Weakness

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

Low platelet count (thrombocytopenia) results in bleeding, especially of the mucous membranes and skin. Symptoms include:

• Bleeding gums
• Easy bruising
• Frequent or severe infections
• Nose bleeds
• Rash--small pinpoint red marks on the skin (petechiae)

Exams and Tests

The health care provider will perform a physical exam.

Blood tests will show:

• Low red blood cell count (anemia)
• Low white blood cell count
• Low reticulocyte count (reticulocytes are immature red blood cell)
• Low platelet count

A bone marrow biopsy shows fewer-than-normal blood cells.

Treatment

Mild cases of aplastic anemia may require no treatment. Symptoms will be treated as appropriate.

In moderate cases, blood transfusions and platelet transfusions will help correct the anemia and the risk of bleeding. However, over time, blood transfusions may stop working. Too much iron may build-up in the body tissues may occur because of the many transfusions. See Hemochromatosis

Severe aplastic anemia occurs when blood-cell counts are very low, and is a life-threatening condition. Bone marrow transplant or stem cell transplant is recommended for severe disease in patients under age 40. However, their donor must be a brother or sister who is a good match. This is called a matched sibling donor.

Older patients and those who do not have a matched sibling donor are given drugs that suppress the immune system, such as anti-thymocyte globulin. This medicine may allow the bone marrow to once again make blood cells. A bone marrow transplant with an unrelated donor may be tried if these medications do not help, or if the disease comes back after getting better.

Outlook (Prognosis)

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

Possible Complications

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

When to Contact a Medical Professional

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.

Prevention

There is no known prevention for idiopathic aplastic anemia.

Alternative Names

Anemia - idiopathic aplastic

References

Castro-Malaspina H, O'Reilly R. Aplastic anemia and related disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 171.

Young NS, Maciejewski JP. Aplastic anemia. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hoffman: Hematology, Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 29.

Update Date: 2/28/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.