Aplastic anemia

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**Aplastic anemia**
*Classifications and external resources*
ICD-10	D 60.-D 61.
ICD-9	284
OMIM	609135
DiseasesDB	866
eMedicine	med/162

Aplastic anemia is a condition where the bone marrow does not produce enough, or any, new cells to replenish the blood cells.

The term 'aplastic' means the marrow suffers from an aplasia that renders it unable function properly. Anemia is the condition of having fewer blood cells than normal, or fewer than needed to function properly. Typically, anemia refers to low red blood cell counts, but aplastic anemia patients have lower counts of all three blood cell types: red blood cells, white blood cells, and platelets.

1 Causes
2 Signs and symptoms
3 Diagnosis
4 Treatment
5 Follow-up
6 See also
7 External links

[edit] Causes

One known cause is an autoimmune disorder, where the white blood cells attack the bone marrow.

In many cases, the etiology is impossible to determine, but aplastic anemia is sometimes associated with exposure to substances such as benzene, radiation, or to the use of certain drugs, including chloramphenicol and phenylbutazone.

[edit] Signs and symptoms

Anemia with malaise, pallor and associated symptoms
Thrombocytopenia (low platelet counts), leading to increased risk of hemorrhage and bruising
Leukopenia (low white blood cell count), leading to increased risk of infection

[edit] Diagnosis

The diagnosis can only be made on bone marrow biopsy. Before this procedure is undertaken, a patient will generally have had other blood tests to find diagnostic clues, including a full blood count, renal function and electrolytes, liver enzymes, thyroid function tests, vitamin B12 and folic acid levels.

[edit] Treatment

Treating aplastic anemia involves suppression of the immune system, an effect achieved by daily medicine intake, or, in more severe cases, a bone marrow transplant, a potential cure but a risky procedure. The transplanted bone marrow replaces the failing bone marrow cells with new ones from a matching donor. The pluripotent stem cells in the bone marrow reconstitute all three blood cell lines, giving the patient a new immune system, red blood cells, and platelets. However, besides the risk of graft failure, there is also a risk that the newly created white blood cells may attack the rest of the body ("graft-versus-host disease").

Medical therapy of aplastic anemia often includes a short course of anti-thymocyte globulin (ATG or anti-lymphocyte globulin) and several months of treatment with cyclosporin to modulate the immune system. Mild chemotherapy with agents such as cyclophosphamide and vincristine may also be effective. Antibodies therapy, such as ATG, targets T-cells, which are believed to attack the bone marrow. Steroids are generally ineffective.

In the past, before the above treatments became available, patients with low leukocyte counts were often confined to a sterile room or bubble (to reduce risk of infections), as in the famed case of Ted DeVita.

[edit] Follow-up

Regular full blood counts are required to determine whether the patient is still in a state of remission.

10-33% of all patients develop the rare disease paroxysmal nocturnal hemoglobinuria (PNH, anemia with thrombopenia and/or thrombosis), which has been explained as an escape mechanism by the bone marrow against destruction by the immune system. Flow cytometry testing is probably warranted in all PNH patients with recurrent aplasia.