Secondary aplastic anemia is a failure of the bone marrow to form enough blood cells. All blood cell types are affected.

Secondary aplastic anemia results from injury to stem cells. Normal stem cells divide and differentiate into all blood cell types. Thus, when stem cells are injured, there is a reduction in red blood cells, white blood cells, and platelets.

This condition can be caused by chemotherapy, drug therapy to suppress the immune system, radiation therapy, toxins such as benzene or arsenic, drugs, pregnancy, and congenital disorders. When the cause is unknown, it is then referred to as idiopathic aplastic anemia.

The disease may be acute or chronic and is usually gets worse unless the cause is removed.

• A low red blood cell count (anemia) leads to fatigue and weakness.
• A low white blood cell count (leukopenia) leads to frequent or severe infections.
• A low platelet count (thrombocytopenia) may result in easy bruising, nose bleeds, bleeding of the gums, and bleeding of internal organs.
• Other symptoms include shortness of breath on exertion, rapid heart rate, and rash.

• A complete blood count (CBC) shows low hematocrit and hemoglobin levels (anemia).
• The reticulocyte count is low.
• The platelet count is low.
• The white blood cell count is low.
• A bone marrow biopsy shows very few cells.

In secondary aplastic anemia, removal of the causative agent is critical, and in some cases can lead to recovery.

Mild cases of aplastic anemia may be treated with supportive care or may require no treatment. Blood transfusions and platelet transfusions will help correct the abnormal blood counts and relieve some symptoms, in moderate cases.

Severe aplastic anemia, which shows up as a very low blood-cell count, is a life-threatening condition. A bone marrow transplant is indicated for younger patients with a severe case of the disease. For older patients, or for those who do not have a matched bone marrow donor, antithymocyte globulin (ATG) is the alternative treatment.

ATG is a horse serum that contains antibodies against human T cells. It is used in an attempt to suppress the body's immune system, allowing the bone marrow to resume its blood-cell generating function. Other medications to suppress the immune system may be used, such as cyclosporine and Cytoxan (cyclophosphamide). Corticosteroids and androgens have also been used.

Untreated aplastic anemia is an illness that leads to rapid death. Bone marrow transplantation has been successful in young people, with a long-term survival rate of 80%. Older people have a survival rate of 40 - 70%.

• Infection
• Cerebral hemorrhage
• Death caused by bleeding, infectious complications of bone marrow transplant, rejection of bone marrow graft, or severe reaction to antithymocyte globulin (ATG)

Call your health care provider if bleeding occurs for no reason.

Secondary aplastic anemia may be an unavoidable consequence of treatments such as chemotherapy. Avoid toxins such as benzene and arsenic if possible.