- Aplastic anemia
OMIM = 609135
eMedicineSubj = med
eMedicineTopic = 162
DiseasesDB = 866
MeshID = D000741
Aplastic anemia is a condition where
bone marrowdoes not produce sufficient new cells to replenish blood cells.
The term 'aplastic' means the marrow suffers from an
aplasiathat renders it unable to function properly. Anemiais the condition of having reduced hemoglobinor red cell concentration in the blood. 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, termed pancytopenia.
One known cause is an
autoimmune disorder, where the white blood cells attack the bone marrow.
In many cases, the
etiologyis 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, carbamazepine, felbamate, phenytoin, quinine, and phenylbutazone. Many drugs are associated with aplasia mainly in the base of case reports but at a very low probability, As an example, chloramphenicol treatment is followed by aplasia in less than 1 in 40,000 treatment courses, and carbamazepine aplasia is even more rare.
Aplastic anemia is present in up to 2% of patients with acute
In some animals aplastic anemia may have other causes. For example, in the
ferret(mustela putorious furo) aplastic anemia is caused by estrogentoxicity. This is because female ferrets are induced ovulators, so mating is required to bring the female out of heat. Unneutered females, if not mated, will remain in heat, and after some time the high levels of estrogen will cause the bone marrow to stop producing red blood cells.
igns and symptoms
Anemiawith malaise, pallorand associated symptoms
Thrombocytopenia(low platelet counts), leading to increased risk of hemorrhageand bruising
Leukopenia(low white blood cell count), leading to increased risk of infection
The condition needs to be differentiated from pure red cell aplasia. In aplastic anemia the patient has pancytopenia (i.e., anemia, neutropenia and thrombocytopenia) resulting in decrease of all formed elements. In contrast, pure red cell aplasia is characterized by reduction in red cells only. The diagnosis can only be confirmed on
bone marrow examination. Before this procedure is undertaken, a patient will generally have had other blood tests to find diagnostic clues, including a complete blood count(CBC), renal functionand electrolytes, liver enzymes, thyroidfunction tests, vitamin B12and folic acidlevels.
Treating immune-mediated aplastic anemia involves suppression of the
immune system, an effect achieved by daily medicineintake, or, in more severe cases, a bone marrow transplant, a potential cure but a risky procedure.cite journal |author=Locasciulli A, Oneto R, Bacigalupo A, "et al" |title=Outcome of patients with acquired aplastic anemia given first line bone marrow transplantation or immunosuppressive treatment in the last decade: a report from the European Group for Blood and Marrow Transplantation (EBMT) |journal=Haematologica |volume=92 |issue=1 |pages=11–8 |year=2007 |pmid=17229630|doi=10.3324/haematol.10075] 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(ALG) and several months of treatment with cyclosporinto modulate the immune system. Mild chemotherapywith agents such as cyclophosphamideand vincristinemay also be effective. Antibodies therapy, such as ATG, targets T-cells, which are believed to attack the bone marrow. Steroidsare 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.cite web |url=http://www.cc.nih.gov/about/news/newsletter/2004/aug04/index.shtml |title=NIH Clinical Center: Clinical Center News, NIH Clinical Center |accessdate=2007-12-04 |format= |work=]
Untreated aplastic anemia is an illness that leads to rapid death, typically within six months. If the disease is diagnosed correctly and initial treatment is begun promptly, then the survival rate for the next five to ten years is substantially improved, and many patients live well beyond that length of time.Fact|date=February 2007
Occasionally, milder cases of the disease resolve on their own. Relapses of previously controlled disease are, however, much more common.
Well-matched bone marrow transplants from siblings have been successful in young, otherwise healthy people, with a long-term survival rate of 80%-90%. Most successful BMT recipients eventually reach a point where they consider themselves cured for all practical purposes, although they need to be compliant with follow-up care permanently.Fact|date=February 2007
Older people (who are generally too frail to undergo bone marrow transplants) and people who are unable to find a good bone marrow match have
five year survival rateof up to 75%.
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 cytometrytesting is performed regularly in people with previous aplastic anemia to monitor for the development of PNH.
Acquired pure red cell aplasia
* [http://www.aamds.org Aplastic Anemia & MDS International Foundation]
* [http://www.mayoclinic.com/health/aplastic-anemia/DS00322 Mayo Clinic]
* [http://medic.med.uth.tmc.edu/ptnt/00001038.htm University of Texas]
* -- Idiopathic aplastic anemia
* -- Secondary aplastic anemia
* [http://www.TheAAT.org.uk The Aplastic Anaemia Trust]
* [http://www.shannonstrust.org.uk/help-given.html Help for Aplastic Anemia sufferers]
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