Anaemia, aplastic

A rare but serious type of anaemia in which the red cells, white cells, and platelets in the blood are all reduced in number. Aplastic anaemia is caused by a failure of the bone marrow to produce stem cells, the initial form of all blood cells. Treatment of cancer with radiotherapy or anticancer drugs can temporarily interfere with the cell-producing ability of bone marrow, as can certain viral infections and other drugs. Long-term exposure to insecticides or benzene fumes may cause more persistent aplastic anaemia, and a moderate to high dose of nuclear radiation is another recognized cause. An autoimmune disorder is responsible in about half of all cases. Aplastic anaemia sometimes develops for no known reason. A low level of red blood cells may cause symptoms common to all types of anaemia, such as fatigue and breathlessness. White-cell deficiency increases susceptibility to infections; platelet deficiency may lead to a tendency to bruise easily, bleeding gums, and nosebleeds. The disorder is usually suspected from blood-test results, particularly a blood count, and is confirmed by a bone marrow biopsy. Blood and platelet transfusions can control symptoms. Immunosuppression is used to treat anaemia due to an autoimmune process. Severe persistent aplastic anaemia may be fatal unless a bone marrow transplant is carried out.