Signs and symptoms
* Anemia with malaise, pallor and associated symptoms such as palpitations * Thrombocytopenia (low platelet counts), leading to increased risk of hemorrhage, bruising and petechiae * Leukopenia (low white blood cell count), leading to increased risk of infection * Reticulocytopenia (low reticulocyte counts)
In many cases, the etiology is considered to be idiopathic (cannot be determined), but one known cause is an autoimmune disorder in whichwhite blood cells attack the bone marrow. Aplastic anemia is also sometimes associated with exposure to toxins such as benzene, or with the use of certain drugs, includingchloramphenicol, carbamazepine, felbamate, phenytoin, quinine, and phenylbutazone. Many drugs are associated with aplasia mainly according to case reports but at a very low probability. As an example, chloramphenicol treatment is followed by aplasia in less than 1 in 40,000 treatment courses, and carbamazepine aplasia is even more rare. Exposure to ionizing radiation from radioactive materials or radiation-producing devices is also associated with the development of aplastic anemia. Aplastic anemia is present in up to 2% of patients with acute viral hepatitis. In some animals aplastic anemia may have other causes. For example, in the ferret (Mustela putorius furo) aplastic anemia is caused byestrogen toxicity. This is because female ferrets are induced ovulators, so mating is required to bring the female out of...