Aplastic anemia


Aplastic anemia

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eMedicineTopic = 162
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Aplastic anemia is a condition where bone marrow does not produce sufficient new cells to replenish blood cells.

The term 'aplastic' means the marrow suffers from an aplasia that renders it unable to function properly. Anemia is the condition of having reduced hemoglobin or 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.

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, 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 viral hepatitis.

In some animals aplastic anemia may have other causes. For example, in the ferret (mustela putorious furo) aplastic anemia is caused by estrogen toxicity. 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

* 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

Diagnosis

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 function and electrolytes, liver enzymes, thyroid function tests, vitamin B12 and folic acid levels.

Treatment

Treating immune-mediated 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.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 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.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=]

Prognosis

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 rate of up to 75%.

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 performed regularly in people with previous aplastic anemia to monitor for the development of PNH.

ee also

* Fanconi anemia
* Acquired pure red cell aplasia

References

External links

* [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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Look at other dictionaries:

  • Aplastic anemia — Anemia due to failure of the bone marrow to produce blood cells, including red and white blood cells as well as platelets. Aplastic anemia frequently occurs without a known cause. Causes of aplastic include chemicals (benzene, toluene in glues,… …   Medical dictionary

  • Aplastic anemia — A*plas tic a*ne mi*a, n. [from {aplasia[2]}.] (Med.) an anemia characterized by substantial reduction or cessation of production of red blood cells and hemoglobin by the bone marrow. Stedman Syn: Ehrlich s anemia; anemia gravis. [PJC] …   The Collaborative International Dictionary of English

  • aplastic anemia — [ā plas′tik] n. [< ModL aplasia, incomplete development (see A 2 & PLASIA) + IC] a form of anemia resulting from a failure of the bone marrow to produce adequate quantities of the essential blood components, including leukocytes and platelets …   English World dictionary

  • aplastic anemia — Pathol. severe anemia due to destruction or depressed functioning of the bone marrow, usually resulting from bone cancer, radiation, or the toxic effects of certain drugs or chemicals. [1930 35; A 6 + PLASTIC] * * * or anemia of bone marrow… …   Universalium

  • aplastic anemia — noun anemia characterized by pancytopenia resulting from failure of the bone marrow; can be caused by neoplasm or by toxic exposure • Syn: ↑aplastic anaemia • Hypernyms: ↑anemia, ↑anaemia …   Useful english dictionary

  • aplastic anemia — noun Date: 1928 anemia that is characterized by defective function of the blood forming organs (as the bone marrow) and is caused by toxic agents (as chemicals or X rays) or is idiopathic in origin …   New Collegiate Dictionary

  • aplastic anemia — a•plas′tic ane′mia [[t]eɪˈplæs tɪk[/t]] n. pat severe anemia due to depressed functioning of the bone marrow, usu. resulting from bone cancer, radiation, or the toxic effects of drugs or chemicals • Etymology: 1930–35 …   From formal English to slang

  • aplastic anemia — A condition in which the bone marrow is unable to produce blood cells …   English dictionary of cancer terms

  • Anemia, aplastic — Anemia due to failure of the bone marrow to produce blood cells, including red and white blood cells as well as platelets. Aplastic anemia frequently occurs without a known cause. Causes of aplastic include chemicals (benzene, toluene in glues,… …   Medical dictionary

  • Anemia — The condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood. The oxygen carrying capacity of the blood is, therefore, decreased. Persons with anemia may feel tired and fatigue …   Medical dictionary