Aplastic anemia (a-PLAS-tik uh-NEE-me-uh) is a blood disorder in which the body's bone marrow doesn't make enough new blood cells. Bone marrow is a sponge-like tissue inside the bones. It makes stem cells that develop into red blood cells, white blood cells, and platelets (PLATE-lets).
Red blood cells carry oxygen to all parts of your body. They also carry carbon dioxide (a waste product) to your lungs to be exhaled. White blood cells help your body fight infections. Platelets are blood cell fragments that stick together to seal small cuts or breaks on blood vessel walls and stop bleeding.
It's normal for blood cells to die. The lifespan of red blood cells is about 120 days. White blood cells live less than a day. Platelets live about 6 days. As a result, your bone marrow must constantly make new blood cells.
If your bone marrow can't make enough new blood cells, many health problems can occur. These problems include irregular heartbeats called arrhythmias (ah-RITH-me-ahs), an enlarged heart, heart failure, infections, and bleeding. Severe aplastic anemia can even cause death.
Aplastic anemia is a type of anemia. The term "anemia" usually refers to a condition in which your blood has a lower than normal number of red blood cells. Anemia also can occur if your red blood cells don't contain enough hemoglobin (HEE-muh-glow-bin). This iron-rich protein helps carry oxygen to your body.
In people who have aplastic anemia, the body doesn't make enough red blood cells, white blood cells, and platelets. This is because the bone marrow's stem cells are damaged. (Aplastic anemia also is called bone marrow failure.)
Many diseases, conditions, and factors can damage the stem cells. These conditions can be acquired or inherited. "Acquired" means you aren't born with the condition, but you develop it. "Inherited" means your parents passed the gene for the condition on to you.
In many people who have aplastic anemia, the cause is unknown.
Aplastic anemia is a rare but serious disorder. It can develop suddenly or slowly. The disorder tends to get worse over time, unless its cause is found and treated. Treatments for aplastic anemia include blood transfusions, blood and marrow stem cell transplants, and medicines.
With prompt and proper care, many people who have aplastic anemia can be successfully treated. Blood and marrow stem cell transplants may offer a cure for some people who have aplastic anemia.
Damage to the bone marrow's stem cells causes aplastic anemia. When stem cells are damaged, they don't grow into healthy blood cells.
The cause of the damage can be acquired or inherited. "Acquired" means you aren't born with the condition, but you develop it. "Inherited" means your parents passed the gene for the condition on to you.
Acquired aplastic anemia is more common, and sometimes it's only temporary. Inherited aplastic anemia is rare.
In many people who have aplastic anemia, the cause is unknown. Some research suggests that stem cell damage may occur because the body's immune system attacks its own cells by mistake.
Many diseases, conditions, and factors can cause aplastic anemia, including:
- Toxins, such as pesticides, arsenic, and benzene.
- Radiation and chemotherapy (treatments for cancer).
- Medicines, such as chloramphenicol (an antibiotic rarely used in the United States).
- Infectious diseases, such as hepatitis, Epstein-Barr virus, cytomegalovirus (si-to-MEG-ah-lo-VI-rus), parvovirus B19, and HIV.
- Autoimmune disorders, such as lupus and rheumatoid arthritis.
- Pregnancy. (Aplastic anemia that occurs during pregnancy often goes away after delivery.)
Sometimes, cancer from another part of the body can spread to the bone and cause aplastic anemia.
Certain inherited conditions can damage the stem cells and lead to aplastic anemia. Examples include Fanconi anemia, Shwachman-Diamond syndrome, dyskeratosis (DIS-ker-ah-TO-sis) congenita, and Diamond-Blackfan anemia.
Aplastic anemia is a rare but serious blood disorder. People of all ages can develop aplastic anemia. However, it's most common in adolescents, young adults, and the elderly. Men and women are equally likely to have it.
The disorder is two to three times more common in Asian countries.
Your risk of aplastic anemia is higher if you:
- Have been exposed to toxins
- Have taken certain medicines or had radiation or chemotherapy (treatments for cancer)
- Have certain infectious diseases, autoimmune disorders, or inherited conditions
For more information, go to "What Causes Aplastic Anemia?"
Signs, Symptoms, and Complications
Lower than normal numbers of red blood cells, white blood cells, and platelets cause most of the signs and symptoms of aplastic anemia.
Signs and Symptoms of Low Blood Cell Counts
Red Blood Cells
The most common symptom of a low red blood cell count is fatigue (tiredness). A lack of hemoglobin in the blood causes fatigue. Hemoglobin is an iron-rich protein in red blood cells. It helps carry oxygen to the body.
A low red blood cell count also can cause shortness of breath; dizziness, especially when standing up; headaches; coldness in your hands or feet; pale skin; and chest pain.
If you don't have enough hemoglobin-carrying red blood cells, your heart has to work harder to move the reduced amount of oxygen in your blood. This can lead to arrhythmias (irregular heartbeats), a heart murmur, an enlarged heart, or even heart failure.
White Blood Cells
White blood cells help fight infections. Signs and symptoms of a low white blood cell count include fevers, frequent infections that can be severe, and flu-like illnesses that linger.
Platelets stick together to seal small cuts or breaks on blood vessel walls and stop bleeding. People who have low platelet counts tend to bruise and bleed easily, and the bleeding may be hard to stop.
Common types of bleeding associated with a low platelet count include nosebleeds, bleeding gums, pinpoint red spots on the skin, and blood in the stool. Women also may have heavy menstrual bleeding.
Other Signs and Symptoms
Aplastic anemia can cause signs and symptoms that aren't directly related to low blood cell counts. Examples include nausea (feeling sick to your stomach) and skin rashes.
Paroxysmal Nocturnal Hemoglobinuria
Some people who have aplastic anemia have a condition called paroxysmal (par-ok-SIZ-mal) nocturnal hemoglobinuria (HE-mo-glo-bi-NOO-re-ah), or PNH. This is a red blood cell disorder. Most people who have PNH don't have any signs or symptoms.
If symptoms do occur, they may include:
- Shortness of breath
- Swelling or pain in the abdomen or swelling in the legs caused by blood clots
- Blood in the urine
- Jaundice (a yellowish color of the skin or whites of the eyes)
In people who have aplastic anemia and PNH, either condition can develop first.
Your doctor will diagnose aplastic anemia based on your medical and family histories, a physical exam, and test results.
Once your doctor knows the cause and severity of the condition, he or she can create a treatment plan for you.
If your primary care doctor thinks you have aplastic anemia, he or she may refer you to a hematologist. A hematologist is a doctor who specializes in treating blood diseases and disorders.
Medical and Family Histories
Your doctor may ask questions about your medical history, such as whether:
- You've had anemia or a condition that can cause anemia
- You have shortness of breath, dizziness, headaches, or other signs and symptoms of anemia
- You've been exposed to certain toxins or medicines
- You've had radiation or chemotherapy (treatments for cancer)
- You've had infections or signs of infections, such as fever
- You bruise or bleed easily
Your doctor also may ask whether any of your family members have had anemia or other blood disorders.
Your doctor will do a physical exam to check for signs of aplastic anemia. He or she will try to find out how severe the disorder is and what's causing it.
The exam may include checking for pale or yellowish skin and signs of bleeding or infection. Your doctor may listen to your heart and lungs for abnormal heartbeats and breathing sounds. He or she also may feel your abdomen to check the size of your liver and feel your legs for swelling.
Many tests are used to diagnose aplastic anemia. These tests help:
- Confirm a diagnosis of aplastic anemia, look for its cause, and find out how severe it is
- Rule out other conditions that may cause similar symptoms
- Check for paroxysmal nocturnal hemoglobinuria (PNH)
Complete Blood Count
Often, the first test used to diagnose aplastic anemia is a complete blood count (CBC). The CBC measures many parts of your blood.
This test checks your hemoglobin and hematocrit (hee-MAT-oh-crit) levels. Hemoglobin is an iron-rich protein in red blood cells. It carries oxygen to the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A low level of hemoglobin or hematocrit is a sign of anemia.
The normal range of these levels varies in certain racial and ethnic populations. Your doctor can explain your test results to you.
The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results may be a sign of aplastic anemia, an infection, or another condition.
Finally, the CBC looks at mean corpuscular (kor-PUS-kyu-lar) volume (MCV). MCV is a measure of the average size of your red blood cells. The results may be a clue as to the cause of your anemia.
A reticulocyte (re-TIK-u-lo-site) count measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate. People who have aplastic anemia have low reticulocyte levels.
Bone Marrow Tests
Bone marrow tests show whether your bone marrow is healthy and making enough blood cells. The two bone marrow tests are aspiration (as-pi-RA-shun) and biopsy.
Bone marrow aspiration may be done to find out if and why your bone marrow isn't making enough blood cells. For this test, your doctor removes a small amount of bone marrow fluid through a needle. The sample is looked at under a microscope to check for faulty cells.
A bone marrow biopsy may be done at the same time as an aspiration or afterward. For this test, your doctor removes a small amount of bone marrow tissue through a needle.
The tissue is checked for the number and types of cells in the bone marrow. In aplastic anemia, the bone marrow has a lower than normal number of all three types of blood cells.
Other conditions can cause symptoms similar to those of aplastic anemia. Thus, other tests may be needed to rule out those conditions. These tests may include:
- X ray, computed tomography (CT) scan, or an ultrasound imaging test. These tests can show enlarged lymph nodes in your abdomen. Enlarged lymph nodes may be a sign of blood cancer. Doctors also may use these tests to look at the kidneys and the bones in the arms and hands, which are sometimes abnormal in young people who have Fanconi anemia. This type of anemia can lead to aplastic anemia.
- Chest x ray. This test creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. A chest x ray may be used to rule out infections.
- Liver tests and viral studies. These tests are used to check for liver diseases and viruses.
- Tests that check vitamin B12 and folate levels in the blood. These tests can help rule out anemia caused by vitamin deficiency.
Your doctor also may recommend blood tests for PNH and to check your immune system for proteins called antibodies. (Antibodies in the immune system that attack your bone marrow cells may cause aplastic anemia.)
Treatments for aplastic anemia include blood transfusions, blood and marrow stem cell transplants, and medicines. These treatments can prevent or limit complications, relieve symptoms, and improve quality of life.
Blood and marrow stem cell transplants may cure the disorder in some people who are eligible for a transplant. Removing a known cause of aplastic anemia, such as exposure to a toxin, also may cure the condition.
Who Needs Treatment
People who have mild or moderate aplastic anemia may not need treatment as long as the condition doesn't get worse. People who have severe aplastic anemia need medical treatment right away to prevent complications.
People who have very severe aplastic anemia need emergency medical care in a hospital. Very severe aplastic anemia can be fatal if it's not treated right away.
Blood transfusions can help keep blood cell counts at acceptable levels. A blood transfusion is a common procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels.
Transfusions require careful matching of donated blood with the recipient's blood.
Blood transfusions help relieve the symptoms of aplastic anemia, but they're not a permanent treatment.
Blood and Marrow Stem Cell Transplants
A blood and marrow stem cell transplant replaces damaged stem cells with healthy ones from another person (a donor).
During the transplant, which is like a blood transfusion, you get donated stem cells through a tube placed in a vein in your chest. Once the stem cells are in your body, they travel to your bone marrow and begin making new blood cells.
Blood and marrow stem cell transplants may cure aplastic anemia in people who can have this type of treatment. The transplant works best in children and young adults with severe aplastic anemia who are in good health and who have matched donors.
Older people may be less able to handle the treatments needed to prepare the body for the transplant. They're also more likely to have complications after the transplant.
If you have aplastic anemia, talk with your doctor about whether a blood and marrow stem cell transplant is an option for you.
If you have aplastic anemia, your doctor may prescribe medicines to:
- Stimulate your bone marrow
- Suppress your immune system
- Prevent and treat infections
Medicines To Stimulate Bone Marrow
Man-made versions of substances that occur naturally in the body can stimulate the bone marrow to make more blood cells. Examples of these types of medicines include erythropoietin and colony-stimulating factors.
These medicines have some risks. You and your doctor will work together to decide whether the benefits of these medicines outweigh the risks. If this treatment works well, it can help you avoid the need for blood transfusions.
Medicines To Suppress the Immune System
Research suggests that aplastic anemia may sometimes occur because the body's immune system attacks its own cells by mistake. For this reason, your doctor may prescribe medicines to suppress your immune system.
These medicines allow your bone marrow to start making blood cells again. They also may help you avoid the need for blood transfusions.
Medicines that suppress the immune system don't cure aplastic anemia. However, they can relieve its symptoms and reduce complications. These medicines often are used for people who can't have blood and marrow stem cell transplants or who are waiting for transplants.
Three medicines—often given together—can suppress the body's immune system. They are antithymocyte globulin (ATG), cyclosporine, and methylprednisolone.
It may take a few months to notice the effects of these medicines. Most often, as blood cell counts rise, symptoms lessen. Blood cell counts in people who respond well to these medicines usually don't reach normal levels. However, the blood cell counts often are high enough to allow people to do their normal activities.
People who have aplastic anemia may need long-term treatment with these medicines.
Medicines that suppress the immune system can have side effects. They also may increase the risk of developing leukemia (lu-KE-me-ah) or myelodysplasia (MI-e-lo-dis-PLA-ze-ah; MDS). Leukemia is a cancer of the blood cells. MDS is a condition in which the bone marrow makes too many faulty blood cells.
Medicines To Prevent and Treat Infections
If you have aplastic anemia, you might be at risk for infections due to low white blood cell counts. Your doctor may prescribe antibiotic and antiviral medicines to prevent and treat infections.
With prompt and proper care, most people who have aplastic anemia can be successfully treated, and some may be cured.
Most people who have the disorder are able to go back to their normal routines after treatment. However, it may take some time to get good results from treatment. You may need repeated treatments, or you may need to try several treatments to find one that works.
It's important to get ongoing medical care to make sure the disorder doesn't worsen and to check for possible complications.
Treatment for aplastic anemia may cause side effects or complications. Talk with your doctor about how to cope with these issues.
People who have aplastic anemia may be at higher risk for infections due to low white blood cell counts. Ask your doctor about ways to lower your risk of infection. For example, you may want to:
- Stay away from people who are sick and avoid large crowds of people.
- Avoid certain foods that can expose you to bacteria, such as uncooked foods.
- Wash your hands often.
- Brush and floss your teeth and get regular dental care to reduce the risk of infections in your mouth and throat.
- Get a yearly flu shot and pneumonia vaccine. Ask your doctor whether these shots will benefit you.
Know the signs of infection, such as fever. Call your doctor right away if you think you have an infection.
Talk with your doctor about what types and amounts of physical activity are safe for you. You may want to avoid activities that cause chest pain or shortness of breath. You also may want to stay away from activities that could result in injuries and bleeding, such as contact sports.
You or your family members may find it helpful to know about resources that can give you emotional support and information about aplastic anemia.
Your doctor or hospital social worker may have information about counseling and support services. They also may be able to refer you to support groups that offer help with financial planning, because treatment for aplastic anemia can be costly.
The National Heart, Lung, and Blood Institute (NHLBI) leads or sponsors many studies aimed at preventing, diagnosing, and treating heart, lung, blood, and sleep disorders.