Idiopathic aplastic anemia is a condition that results from injury to the stem cell, a cell that gives rise to other cell types after it divides. Consequently, there is a reduction in all cell types -- red blood cells, white blood cells and platelets -- with this type of anemia, which is called pancytopenia.

The cause of idiopathic aplastic anemia is unknown, but is thought to be an autoimmune process (the body reacting against its own cells). Causes of other types of aplastic anemia may be chemotherapy, radiation therapy, toxins, drugs, pregnancy, congenital disorder, or systemic lupus erythematosus.

Symptoms arise as the consequence of bone marrow failure. Anemia (low red blood cell count) leads to fatigue and weakness. Low white blood cell count, or leukopenia, causes an increased risk of infection. Low platelet count, or thrombocytopenia, results in bleeding, especially of mucus membranes and skin.

The disease may be acute or chronic, and is almost always progressive. Risk factors are unknown.

• Fatigue
• Pallor
• Shortness of breath on exertion
• Rapid heart rate
• Easy bruising
• Nose bleeds
• Bleeding gums
• Prolonged bleeding
• Frequent or severe infections
• Lymph nodes may be enlarged (rare)

• Anemia, or low red blood cells
• Low white blood cell count
• Low, reticulocyte count, or red blood cell precursors
• Low platelet count
• Bone marrow biopsy shows few blood cells

Mild cases of aplastic anemia are treated with supportive care. Blood transfusions and platelet transfusions help correct the abnormal blood counts and relieve some symptoms.

Severe aplastic anemia, as evidenced by very low blood cell counts, is a life-threatening condition. Bone marrow transplant is indicated for severe disease in younger patients.

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 and 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.

Severe infections or bleeding may develop.

Complications of treatment may include graft failure or graft vs. host disease, and an autoimmune disease, after bone marrow transplant. Patients can have reactions to ATG.