Aplastic Or Hypoplastic Anemias

Aplastic and hypoplastic anemias are potentially fatal and result from injury to or destruction of stem cells in bone marrow or the bone marrow matrix, causing pancytopenia (anemia, leukopenia, thrombocytopenia) and bone marrow hypoplasia.

Although often used interchangeably with other terms for bone marrow failure, aplastic anemias correctly refer to pancytopenia resulting from the decreased functional capacity of a hypoplastic, fatty bone marrow. These disorders usually produce fatal bleeding or infection, particularly when they're idiopathic or stem from chloramphenicol use or infectious hepatitis. Mortality for aplastic anemias with severe pancytopenia is 80% to 90%.

Causes

Aplastic anemias usually develop when damaged or destroyed stem cells inhibit red blood cell (RBC) production. Less commonly, they develop when damaged bone marrow microvasculature creates an unfavorable environment for cell growth and maturation. About half of such anemias result from drugs (such as chloramphenicol), toxic agents (such as benzene), or radiation. The rest may result from , immunologic factors (suspected but unconfirmed), severe disease (especially hepatitis), viral infection ( especially in children), and preleukemic and neoplastic infiltration of bone marrow.

Idiopathic anemias may be congenital. Two such forms of aplastic anemia have been identified: Congenital hypoplastic anemia (Blackfan-Diamond anemia) develops between ages 2 and 3 months, and Fanconi's syndrome, between birth and age 10. In the absence of a consistent familial or genetic history of aplastic anemia, researchers suspect that these congenital abnormalities result from an induced change in fetal development, such as in maternal rubella cytomegalovirus infection.

Symptoms

The following are the most common symptoms of aplastic anemia. However, each individual may experience symptoms differently. Symptoms may include:

• headache
• dizziness
• nausea
• shortness of breath
• bruising
• lack of energy or tiring easily (fatigue)
• abnormal paleness or lack of color of the skin
• blood in stool
• nosebleeds
• bleeding gums
• fevers
• sinus tenderness
• enlarged liver or spleen
• oral thrush - white patches on a red, moist, swollen surface, occurring anywhere in the mouth.

The symptoms of aplastic anemia may resemble other blood disorders or medical problems. Always consult your physician for a diagnosis.

Diagnostic tests

In addition to a complete medical history and physical examination, diagnostic procedures for anemia include additional blood tests and a bone marrow biopsy.

Treatment

Effective treatment must eliminate any identifiable cause and provide vigorous supportive measures, such as packed RBC, platelet, and experimental histocompatibility antigen-matched leukocyte transfusions. Even after elimination of the cause, recovery can take months or may never occur. Bone marrow transplantation is the treatment of choice for anemia due to severe aplasia and for patients who need constant RBC transfusions.

The patient with low leukocyte counts is at risk for infection. Prevention of infection may range from frequent hand washing to filtered air flow. The infection itself may require specific antibiotics; however, they are not given prophylactically because they tend to encourage resistant strains of organisms. Patients with low hemoglobin levels may need respiratory support with oxygen in addition to blood transfusions.

Other appropriate forms of treatment include corticosteroids to stimulate erythroid production (successful in children, unsuccessful in adults); marrow­stimulating agents, such as androgens (which are controversial); antilymphocyte globulin (experimental); and immunosuppressant agents (if the patient doesn't respond to other therapy).

A group of agents called colony-stimulating factors encourage the growth of specific cellular components and show some promise in trials of patients who have received chemotherapy or radiation therapy. These agents include granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and erythropoietic stimulating factor.

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