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

Secondary aplastic anemia results from injury to blood stem cells. Normal blood stem cells divide and differentiate into all blood cell types. Thus, when blood 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 disorders present birth. When the cause is unknown, it is then referred to as idiopathic aplastic anemia.

The disease may be acute or chronic and 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 during physical activity, 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.