An Overview of Aplastic Anemia

How to Diagnose and Treat This Bone Marrow Disorder

In aplastic anemia (AA), the bone marrow stops making enough red blood cells, white blood cells, and platelets. Aplastic anemia may appear at any age but is diagnosed more often in children and young adults. The disorder occurs in about two to six individuals per million population worldwide.

About 20% of individuals develop aplastic anemia as part of an inherited syndrome such as Fanconi anemia, dyskeratosis congenita, or Blackfan Diamond anemia. Most individuals (80%) have acquired aplastic anemia, meaning that it was caused by infections such as hepatitis or Epstein-Barr virus, toxic exposure to radiation and chemicals, or drugs such as chloramphenicol or phenylbutazone. Research suggests aplastic anemia may be the result of an autoimmune disorder.

Nurse taking blood from patient in hospital
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The symptoms of aplastic anemia come on slowly. The symptoms are related to the low levels of blood cells:

  • Low numbers of red blood cells cause anemia, with symptoms such as a headache, dizziness, fatigue, and paleness (pallor)
  • Low numbers of platelets (necessary for blood clotting) cause unusual bleeding from the gums, nose, or bruising under the skin (small spots called petechiae)
  • Low numbers of white blood cells (necessary for fighting infection) causes recurrent infections or lingering illness.


The symptoms of aplastic anemia often point the way to a diagnosis. The physician will obtain a complete blood cell count (CBC) and the blood will be examined under the microscope (blood smear). The CBC will show the low levels of red cells, white cells, and platelets in the blood. Looking at the cells under the microscope will distinguish aplastic anemia from other blood disorders.

In addition to the blood tests, a bone marrow biopsy (sample) will be taken and examined under the microscope. In aplastic anemia, it will show few new blood cells being formed. Examining the bone marrow also helps distinguish aplastic anemia from other bone marrow disorders, such as myelodysplastic disorder or leukemia.


Classifying or staging the disease is based on the criteria of the International Aplastic Anemia Study Group, which defines levels according to the numbers of blood cells present in the blood tests and bone marrow biopsy. Aplastic anemia is classified as moderate (MAA), severe (SAA), or very severe (VSAA).


For young individuals with aplastic anemia, a bone marrow or stem cell transplant replaces the defective bone marrow with healthy blood-forming cells. Transplantation carries many risks, so it is sometimes not used as a treatment for middle-aged or elderly individuals. About 80% of individuals who receive a bone marrow transplant have a complete recovery.

For older individuals, treatment of aplastic anemia focuses on suppressing the immune system with Atgam (anti-thymocyte globulin), Sandimmune (cyclosporine), or Solu-Medrol (methylprednisolone), alone or in combination.

The response to drug treatment is slow, and about one-third of individuals have a relapse, which may respond to a second round of medication. Individuals with aplastic anemia will be treated by a blood specialist (hematologist).

Since individuals with aplastic anemia have low numbers of white blood cells, they are at high risk for infection. Therefore, preventing infections, and treating them quickly once they occur, is important.

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  • "Aplastic Anemia." About the Diseases. 10 Nov 2006. Aplastic Anemia & MDS International Foundation, Inc.