Aplastic anemia is a bone marrow failure syndrome characterized by peripheral pancytopenia and marrow hypoplasia. Paul Ehrlich, MD, introduced the concept of aplastic anemia in 1888 when he studied the case of a pregnant woman who died of bone marrow failure.
Within the cavity of many of your bones, such as your pelvic bones, is a red, spongy material called bone marrow.
Bone marrow has a critical function. It contains special cells called stem cells, which are precursors of other cells. Stem cells in the bone marrow produce blood cells red cells, white cells and platelets that eventually leave the bone marrow and enter your bloodstream. Stem cells also make more stem cells.
Your bone marrow needs to continually produce new blood cells of all types to replace old ones. Blood cells live for only a short period once they leave the bone marrow and enter your blood. Red blood cells live about four months, platelets less than a week and most white blood cells a day or less before they're used and absorbed by your body.
Normally, your bone marrow supplies the right numbers of blood cells to keep you healthy. Aplastic anemia develops when damage occurs to your bone marrow, slowing or shutting down the production of new blood cells a serious problem. Factors that can temporarily or permanently injure bone marrow include:
In aplastic anemia, the bone marrow is described in medical terms as aplastic or hypoplastic meaning that it's empty, or containing very few blood cells.
Aplastic anemia is sometimes confused with myelodysplastic syndrome. In this group of disorders, the bone marrow produces new blood cells, but they're deformed and underdeveloped. The bone marrow in myelodysplastic syndrome is sometimes called hyperplastic meaning that it's packed with blood cells. But some people with myelodysplastic syndrome have empty marrow that's difficult to distinguish from aplastic anemia.
Because myelodysplastic syndrome also results in a shortage of healthy blood cells, it causes signs and symptoms similar to those of aplastic anemia fatigue, unexplained bruising and easy bleeding. Myelodysplastic syndrome has many causes, including possibly exposure to radiation or toxic chemicals.
Doctors distinguish myelodysplastic syndrome from aplastic anemia through careful diagnosis, a bone marrow biopsy and genetic analysis of the bone marrow. Myelodysplastic syndrome which is more common in people older than 60 is also serious and treated with some of the same therapies as those used to treat aplastic anemia.
Additionally, about 30 percent of people with aplastic anemia also have a rare disorder known as paroxysmal nocturnal hemoglobinuria. Marrow cells become overly sensitive to the immune system in this disorder, destroying red blood cells and causing defective platelets to form.
Fanconi's anemia is an extremely rare, inherited disease that leads to aplastic anemia. Children born with it tend to be smaller than average and have birth defects, such as underdeveloped limbs. The disease is diagnosed with the help of blood tests. It's treated with medications and occasionally a bone marrow transplant.
Aplastic anemia is rare. Factors that can increase your risk include:
Aplastic anemia can develop at any age, but it's more commonly diagnosed in children and young adults.
Screening and diagnosis
Doctors diagnose aplastic anemia through blood tests and a bone marrow biopsy.
Normally, red blood cell, white blood cell and platelet levels stay within a certain range. Your doctor may suspect aplastic anemia when all three of these blood cell levels are very low.
Many conditions can cause low blood cell counts, but usually of just one type of blood cell. For example, other types of anemia cause a decrease in red blood cells. If you have an infection, your white blood cell count alone may be low.
To confirm a diagnosis of aplastic anemia, you'll need a bone marrow biopsy. In this procedure, a doctor uses a needle to remove a small sample of bone marrow from a large bone in your body, such as your hipbone. The bone marrow sample is examined under a microscope to rule out other blood-related diseases. In aplastic anemia, bone marrow contains fewer blood cells than normal. The very few cells that are present, however, are normal. In diseases such as leukemia and myelodysplastic syndrome, the bone marrow is full of abnormal blood cells.
The initial diagnosis of aplastic anemia may be made by your doctor or at a local hospital. But for further evaluation and treatment, you'll likely be referred to a doctor who specializes in blood diseases (hematologist) or to a special treatment center for aplastic anemia.
Once you've received a diagnosis of aplastic anemia, you may need additional tests to determine an underlying cause.