Aplastic anemia is a rare disease caused by a decrease in the number of all types of blood cells that bone marrow produces. 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, 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. This form of anemia can be severe or even fatal.
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.
- Prolonged bleeding
- Frequent nosebleeds and bleeding gums
- Easy bruising
- Pinpoint red spots on skin
- Blood in the stool
- Heavy menstrual bleeding
There may also be signs and symptoms due to a low WBC count:
- Increased frequency 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 like arsenic, benzene (found in gasoline), or pesticides
- Cancer therapy (radiation or chemotherapy)
- Autoimmune disorders such as lupus or rheumatoid arthritis
- Viral infections such as hepatitis, HIV, EBV, or CMV
- Medicines such as chloramphenicol (an antibiotic rarely used in the U.S.)
Rarely, aplastic anemia is due to an inherited (genetic) disorder such as Fanconi anemia. For more on this rare blood condition, see the Fanconi Anemia Research web site. Other genetic disorders leading to aplastic anemia include Shwachman-Diamond syndrome and dyskeratosis congenita.
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 low
- Erythropoietin—usually increased in aplastic anemia
- Bone marrow aspiration or biopsy will show a decrease in the number of all types of cells.
- Tests for infections such as hepatitis, HIV, EBV, CMV help to determine the cause.
- Tests for arsenic (a heavy metal) and other toxins
- Iron tests or tests for vitamin B12 may be done to rule out other causes.
- 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 (e.g., chloramphenicol) or prior treatment for cancer. Some cases of aplastic anemia are temporary while others have lasting damage to the bone marrow. Therefore, the 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.