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. Estimates vary, but between 1.5 and about seven cases are diagnosed per million people each year.

Some individuals develop aplastic anemia as part of an inherited syndrome such as Fanconi anemia, dyskeratosis congenita, or Blackfan Diamond anemia. Many individuals 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 86% 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) or Sandimmune (cyclosporine) 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.

13 Sources
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  1. Peslak SA, Olson T, Babushok DV. Diagnosis and treatment of aplastic anemia. Curr Treat Options in Oncol. 2017;18(12):70. doi: 10.1007/s11864-017-0511-z

  2. Vaht K, Göransson M, Carlson K, et al. Incidence and outcome of acquired aplastic anemia: real-world data from patients diagnosed in Sweden from 2000–2011. Haematologica. 2017;102(10):1683-1690. doi: 10.3324/haematol.2017.169862

  3. Alter BP. Inherited bone marrow failure syndromes: considerations pre- and posttransplant.Hematology. 2017;2017(1):88-95. doi: 10.1182/asheducation-2017.1.88

  4. The Aplastic Anemia and MDS International Foundation. Aplastic Anemia Causes.

  5. Risitano AM. (Auto-)Immune signature in aplastic anemia. Haematologica. 2018;103(5):747-749. doi: 10.3324/haematol.2018.190884

  6. National Heart, Lung, and Blood Institute. Aplastic Anemia.

  7. National Institute of Diabetes and Disgestive and Kidney Diseases. Diagnosis of Aplastic Anemia & Melodysplastic Syndromes.

  8. Patel BJ, Barot SV, Kuzmanovic T, et al. Distinctive and common features of moderate aplastic anaemia. Br J Haematol. 2020;189(5):967-975. doi:10.1111/bjh.16460

  9. Grimaldi F, Potter V, Perez-Abellan P, et al. Mixed T Cell Chimerism After Allogeneic Hematopoietic Stem Cell Transplantation for Severe Aplastic Anemia Using an Alemtuzumab-Containing Regimen Is Shaped by Persistence of Recipient CD8 T Cells. Biol Blood Marrow Transplant. 2017;23(2):293-299. doi:10.1016/j.bbmt.2016.11.003

  10. Ali N, Adil SN, Shaikh MU. Autologous hematopoietic stem cell transplantation-10 years of data from a developing country. Stem Cells Transl Med. 2015;4(8):873-877. doi: 10.5966/sctm.2015-0015

  11. Tjon JML, Langemeijer SMC, Halkes CJM. Anti thymocyte globulin-based treatment for acquired bone marrow failure in adults. Cells. 2021;10(11):2905. doi: 10.3390/cells10112905

  12. Shetty M, Narendra AMVR, Adiraju KP, Modugu NR. Study of aplastic anaemia with cyclosporine in resource poor setting. J Clin Diagn Res. 2016;10(6):OC15-18. doi: 10.7860/JCDR/2016/16144.7952

  13. Lertpongpiroon R, Rattarittamrong E, Rattanathammethee T, et al. Infections in patients with aplastic anemia in chiang mai university. BMC Hematol. 2018;18(1):35. doi: 10.1186/s12878-018-0129-9

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

By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.