Aplastic Anemias
Aplastic anemia is a rare disease, caused by a decrease in the number of all types of blood cells produced by the bone marrow. Normally, the bone marrow produces a sufficient number of new red blood cells (RBCs), white blood cells (WBCs), and platelets for normal body function. Each type of cell enters the blood stream, circulates, and then dies within a certain time frame. For example, the normal lifespan of RBCs is about 120 days. If the bone marrow is not able to produce enough blood cells to replace those that die, a number of symptoms, including those due to anemia, may result.
Symptoms of aplastic anemia can appear abruptly or can develop more slowly. Some general symptoms that are common to different types of anemia may appear first and are due to the decrease in number of RBCs. These include:
- Feeling of tiredness, fatigue
- Lack of energy
Some additional signs and symptoms that occur with aplastic anemia include those due to decreased platelets:
- Prolonged bleeding
- Frequent nosebleeds
- Bleeding gums
- Easy bruising
and due to a low WBC count:
- Increased number and severity of infections
Causes of aplastic anemia usually have to do with damage to the stem cells in the bone marrow that are responsible for blood cell production. Some factors that may be involved with bone marrow damage and that can lead to aplastic anemia include:
- Exposure to toxic substances such as arsenic, benzene or pesticides
- Cancer therapy (radiation or chemotherapy)
- Autoimmune disorders such as lupus or rheumatoid arthritis
- Viral infections such as hepatitis, EBV, HIV, CMV, or parvovirus B19
Rarely, aplastic anemia is due to an inherited (genetic) disorder such as Fanconi anemia. For more on this condition, see the Faconi Anemia Research web site.
Laboratory Tests
The initial test for anemia, the complete blood count (CBC), may reveal many abnormal results.
- Hemoglobin and/or hematocrit may be low.
- RBC and WBC counts are low.
- Platelet count is low.
- Red blood cell indices are usually normal.
- The differential white blood count shows a decrease in most types of cells but not lymphocytes.
Some additional tests that may be performed to help determine the type and cause of anemia include:
- Reticulocyte count—result is usually low.
- Erythropoietin—usually increased in aplastic anemia.
- A bone marrow aspiration will show a decrease in the number of all types of mature cells.
- Tests for infections such as hepatitis, EBV, CMV help to determine the cause.
- Test for arsenic (a heavy metal) and other toxins
- Iron tests or tests for vitamin B12 may be done to rule out other causes.
- Antibody tests such as ANA to determine if the cause is autoimmune disease.
A physical examination or complete medical history may reveal possible causes for aplastic anemia such as exposure to toxins or certain drugs (for example, chloramphenicol) or prior treatment for cancer. Some cases of aplastic anemia are temporary while others have lasting damage to the bone marrow. Treatment depends on the cause. Reducing or eliminating exposure to certain toxins or drugs may help resolve the condition. Medications may be given to stimulate bone marrow production, to treat infections, or to suppress the immune system in cases of autoimmune disorders. Blood transfusions and a bone marrow transplant may be needed in severe cases.
