Minggu, 23 Desember 2012

Aplastic anemia

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Aplastic anemia

Definition  :
Aplastic anemia

Aplastic anemia is a condition that occurs when your body stops producing enough new blood cells. Aplastic anemia leaves you feeling fatigued and at higher risk of infections and uncontrolled bleeding.

A rare and serious condition, aplastic anemia can develop at any age. Aplastic anemia may occur suddenly, or it can occur slowly and get worse over a long period of time. Treatment for aplastic anemia may include medications, blood transfusions or a stem cell transplant.

Symptoms:

Aplastic anemia symptoms result from a shortage of one or more types of blood cells. Signs and symptoms may include:
  • Fatigue
  • Shortness of breath with exertion
  • Rapid or irregular heart rate
  • Pale skin
  • Frequent or prolonged infections
  • Unexplained or easy bruising
  • Nosebleeds and bleeding gums
  • Prolonged bleeding from cuts
  • Skin rash
  • Dizziness
  • Headache
Aplastic anemia can progress slowly over weeks or months, or it may come on suddenly. The illness may be brief, or it may become chronic. Aplastic anemia can be very severe and even fatal.

Causes:

Aplastic anemia develops when damage occurs to your bone marrow, slowing or shutting down the production of new blood cells. Bone marrow is a red, spongy material inside your bones that produces stem cells, which give rise to other cells. Stem cells in the bone marrow produce blood cells — red cells, white cells and platelets. In aplastic anemia, the bone marrow is described in medical terms as aplastic or hypoplastic — meaning that it's empty (aplastic) or contains very few blood cells (hypoplastic).

Factors that can temporarily or permanently injure bone marrow and affect blood cell production include:
  • Radiation and chemotherapy treatments. While these cancer-fighting therapies kill cancer cells, they can also damage healthy cells, including stem cells in bone marrow. Aplastic anemia can be a temporary side effect of these treatments.
  • Exposure to toxic chemicals. Exposure to toxic chemicals, such as some used in pesticides and insecticides, may cause aplastic anemia. Exposure to benzene — an ingredient in gasoline — also has been linked to aplastic anemia. This type of anemia sometimes gets better on its own if you avoid repeated exposure to the chemicals that caused your initial illness.
  • Use of certain drugs. Some medications, such as those used to treat rheumatoid arthritis and some antibiotics, can cause aplastic anemia.
  • Autoimmune disorders. An autoimmune disorder, in which your immune system begins attacking healthy cells, may involve stem cells in your bone marrow.
  • A viral infection. Viral infections that affect bone marrow may play a role in the development of aplastic anemia in some people. Viruses that have been linked to the development of aplastic anemia include hepatitis, Epstein-Barr, cytomegalovirus, parvovirus B19 and HIV.
  • Pregnancy. Aplastic anemia that occurs in pregnancy may be related to an autoimmune problem — your immune system may attack your bone marrow during pregnancy.
  • Unknown factors. In many cases, doctors aren't able to identify the cause of aplastic anemia. This is called idiopathic aplastic anemia.
Confusion with myelodysplastic syndrome
Aplastic anemia can be mistaken for a condition called myelodysplastic syndrome. In this group of disorders, the bone marrow produces new blood cells, but they're deformed and underdeveloped. The bone marrow in myelodysplastic syndrome is sometimes called hyperplastic — meaning that it's packed with blood cells. But some people with myelodysplastic syndrome have empty marrow that's difficult to distinguish from aplastic anemia.

Connections with other rare disorders
Some people with aplastic anemia also have a rare disorder known as paroxysmal nocturnal hemoglobinuria. This disorder causes red blood cells to break down too soon. Paroxysmal nocturnal hemoglobinuria can lead to aplastic anemia, or aplastic anemia can evolve into paroxysmal nocturnal hemoglobinuria
.
Fanconi's anemia is a rare, inherited disease that leads to aplastic anemia. Children born with it tend to be smaller than average and have birth defects, such as underdeveloped limbs. The disease is diagnosed with the help of blood tests.

Treatments and drugs:
 
Treatments for aplastic anemia may include observation for mild cases, blood transfusions and medications for more serious cases, and, in severe cases, bone marrow transplantation. Severe aplastic anemia, in which your blood cell counts are extremely low, is life-threatening and requires immediate hospitalization for treatment.

Blood transfusions
Treatment for aplastic anemia usually involves blood transfusions to control bleeding and relieve anemia symptoms. Blood transfusions aren't a cure for aplastic anemia. But they do relieve signs and symptoms by providing blood cells that your bone marrow isn't producing. A transfusion may include:
  • Red blood cells. Transfusions of red blood cells raise red blood cell counts. This helps relieve anemia and fatigue.
  • Platelets. Transfusions of platelets help prevent excessive bleeding.
While there's generally no limit to the number of blood cell transfusions you can have, complications can sometimes arise with multiple transfusions. Transfused red blood cells contain iron that can accumulate in your body and can damage vital organs if an iron overload isn't treated. Medications can help your body get rid of excess iron. Another possible complication is that over time, your body may develop antibodies to transfused blood cells, making them less effective at relieving symptoms.

Stem cell transplant
A stem cell transplant to rebuild the bone marrow with stem cells from a donor may offer the only successful treatment option for people with severe aplastic anemia. A stem cell transplant, which is also called a bone marrow transplant, is generally the treatment of choice for people who are younger and have a matching donor — most often a sibling.

If a donor is found, your diseased bone marrow is first depleted with radiation or chemotherapy. Healthy stem cells from the donor are filtered from the blood. The healthy stem cells are injected intravenously into your bloodstream, where they migrate to the bone marrow cavities and begin generating new blood cells. The procedure requires a lengthy hospital stay. After the transplant, you'll receive drugs to help prevent rejection of the donated stem cells.

A stem cell transplant carries risks. There's a chance that your body may reject the transplant, leading to life-threatening complications. In addition, not everyone is a candidate for transplantation or can find a suitable donor.

Immunosuppressants
For people who can't undergo a bone marrow transplant or for those whose aplastic anemia may be due to an autoimmune disorder, treatment may involve drugs that alter or suppress the immune system (immunosuppressants).

Drugs such as cyclosporine (Gengraf, Neoral, Sandimmune) and anti-thymocyte globulin (Thymoglobulin) are examples. These drugs suppress the activity of immune cells that are damaging your bone marrow. This helps your bone marrow recover and generate new blood cells. Cyclosporine and anti-thymocyte globulin are often used in combination.
Corticosteroids, such as methylprednisolone (Medrol, Solu-Medrol), are often given at the same time as these drugs.

Immune-suppressing drugs can be very effective at treating aplastic anemia. The downside is that these drugs further weaken your immune system. It's also possible that after you stop taking these drugs, aplastic anemia may return.


Bone marrow stimulants
Certain drugs — including colony-stimulating factors, such as sargramostim (Leukine), filgrastim (Neupogen) and pegfilgrastim (Neulasta), and epoetin alfa (Epogen, Procrit) — may help stimulate the bone marrow to produce new blood cells. Growth factors are often used in combination with immune-suppressing drugs.


Antibiotics, antivirals Having aplastic anemia weakens your immune system. You have fewer white blood cells in circulation to fight off germs. This leaves you susceptible to infections.
At the first sign of infection, such as a fever, see your doctor. You don't want the infection to get worse, because it could prove life-threatening. If you have severe aplastic anemia, your doctor may give you antibiotics or antiviral medications to help prevent infections.

Other treatments
Aplastic anemia caused by radiation and chemotherapy treatments for cancer usually improves once you complete those treatments. The same is true for most other drugs that induce aplastic anemia.
Pregnant women with aplastic anemia are treated with blood transfusions. For many women, pregnancy-related aplastic anemia improves once the pregnancy ends. If that doesn't happen, treatment is still necessary.

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