What Is Aplastic Anemia?
Aplastic anemia (a-PLAS-tik uh-NEE-me-uh) is a rare
and serious blood disorder in which bone marrow stops making enough new blood
cells. Bone marrowthe spongy material inside bonesmakes new
blood cells called stem cells. Stem cells normally develop into three main
types of blood cells: red blood cells, white blood cells, and platelets. Each
type of blood cell has its own functions in the body.
It is normal for blood cells to die. The lifespan of
red blood cells is about 120 days. White blood cells live less than 1 day.
Platelets live about 6 days. As a result, bone marrow must constantly make new
blood cells. The term "anemia"
is most often used to mean a condition in which a persons number of red
blood cells is too low or their red blood cells do not carry enough hemoglobin
(HEE-muh-glow-bin). However, in aplastic anemia, normal production of all blood
cellsred cells, white cells, and plateletsslows or stops. This is
because the stem cells have been damaged. The cause of this damage is often
unknown.
Effects of Aplastic Anemia on the Body
A shortage of any one of the three main types of
blood cells will have an effect on the body. In aplastic anemia, however, the
body must cope with a shortage of all three types of blood cells. Severe
aplastic anemia that is not treated promptly can be fatal.
The effect on the body of a shortage of each type of
blood cell is described below:
- Too few red blood cells. Red blood cells contain
hemoglobin, which is an iron-rich protein that gives blood its red color.
Hemoglobin carries oxygen from the lungs to the rest of the body. Red blood
cells also remove carbon dioxide (a waste product) from cells and carry it to
the lungs to be exhaled. If there are not enough red blood cells, too little
oxygen is carried to the body and too little carbon dioxide is carried away.
People who have a low red blood cell count often feel tired because the body is
not getting enough oxygen. An untreated or severely low red blood cell count
can lead to many problems. The heart has to work harder to pump blood to get
enough oxygen to the bodys organs and tissues. Over time, this stress on
the heart can cause fast or irregular heartbeats, an enlarged heart, or even
heart
failure.
- Too few white blood cells. White blood cells
fight infection and are an important part of the bodys defense system.
When the number of white blood cells in the blood is lower than normal, the
body is less able to fight infections. A person may become ill more often, and
the illness may be very severe or last a long time.
- Too few platelets. Platelets are needed to help
blood clot. If the platelet count is low, blood cannot clot normally. A person
with a low platelet count may bruise or bleed easily, and the bleeding may be
hard to stop.
Important General Information
Aplastic anemia is a rare condition. In the United
States, about 5001,000 people develop this type of anemia each year. It
is two to three times more common in Asian countries.
The two main types of aplastic anemia are acquired
and hereditary. Acquired means a person develops the condition during his or
her lifetime. Hereditary means a person is born with the condition. Acquired
aplastic anemia is the most common type, and it is sometimes a temporary
condition. It can be triggered by exposure to:
- Toxic chemicals
- Chemotherapy drugs
- Radiation
- Virus infections
However, the cause of acquired aplastic anemia is
often not known.
Hereditary aplastic anemia is rare. It occurs with
some inherited conditions, such as Fanconi anemia.
Severity of Aplastic Anemia
Aplastic anemia can begin suddenly or develop
slowly. It tends to get worse over time, except when a cause can be found and
removed. Its severity ranges from mild to very severe.
- People with mild or moderate aplastic anemia have
low blood counts that the doctor will check often. If the blood counts do not
get worse, treatment may not be needed.
- People with severe aplastic anemia have very low
blood counts. The condition can become life threatening if it is not
treated.
- People with very severe aplastic anemia have
extremely low blood counts. This condition is life threatening. It needs
emergency hospital treatment.
Although aplastic anemia is not cancer, the
treatments for it are similar to those used for some types of cancer.
Treatments include blood transfusions and bone marrow transplants. Treatments
also include medicines to suppress the immune system, stimulate the bone
marrow, and treat infections.
Outlook
Many people with aplastic anemia can be treated
successfully if they have prompt and appropriate treatment. Some people with
aplastic anemia can be cured with a bone marrow transplant.
Other Names for Aplastic Anemia
What Causes Aplastic Anemia?
Aplastic anemia is caused by damage to stem cells in
the bone marrow. Stem cells normally develop into three types of blood cells:
red blood cells, white blood cells, and platelets. When stem cells are damaged,
they do not grow into healthy blood cells.
In more than half of people with aplastic anemia,
the cause of the damage to stem cells is unknown. Some research suggests that
stem cell damage may occur because the bodys immune system attacks its
own cells by mistake.
Causes of Acquired Aplastic Anemia
The cause of acquired aplastic anemia has been
linked to outside agents, as well as to diseases. Outside agents include toxins
such as pesticides, arsenic, and benzene; radiation and chemotherapy used to
treat cancer; and medicines such as chloramphenicol, an antibiotic now rarely
used in the United States. Infectious diseases also can cause aplastic anemia.
Some of these diseases are hepatitis, Epstein-Barr virus, cytomegalovirus
(si-to-MEG-a-lo-VI-rus), parvovirus B19, and HIV. Autoimmune diseases, such as
lupus and rheumatoid arthritis (ROO-ma-toyd ar-THRI-tis), also can cause this
condition.
Causes of Hereditary Aplastic Anemia
Some inherited genetic disorders can lead to
aplastic anemia. These include Fanconi anemia, Shwachman-Diamond syndrome, and
dyskeratosis congenita.
Who Is At Risk for Aplastic Anemia?
Aplastic anemia is a rare condition. In the United
States, about 5001,000 people develop this type of anemia each year. It
is two to three times more common in Asian countries.
People of all ages can develop aplastic anemia. Men
and women are equally likely to have it. It is most common in adolescents and
young adults as well as the elderly.
Aplastic anemia is more likely to develop in people
who:
- Have been exposed to toxins, certain drugs, or
radiation
- Are infected with viruses, such as hepatitis and
HIV
- Have an inherited disorder, such as Fanconi
anemia, or an autoimmune disease
What Are the Signs and Symptoms of Aplastic
Anemia?
Most of the signs and symptoms of aplastic anemia
are caused by low numbers of each of the three main types of blood
cellsred blood cells, white blood cells, and platelets. Other signs and
symptoms are not linked to a shortage of any particular blood cell type.
Too Few Red Blood Cells
The most common symptom of a low red blood cell
count is low energy and feeling tired. This is caused by lack of enough
hemoglobin, an iron-rich protein contained in red blood cells that carries
oxygen to the body. A lack of enough oxygen in the blood can cause people to
feel short of breath and dizzy, especially when standing up. Since the heart
must work harder to circulate the reduced amount of oxygen, symptoms also can
include a rapid or irregular heartbeat or an extra or unusual sound heard
during the heartbeat (heart
murmur).
The hemoglobin in red blood cells gives blood its
red color. Lack of hemoglobin due to a low red blood cell count can lead to
pale skin, gums, and nail beds.
Too Few White Blood Cells
White blood cells help fight infections. Signs and
symptoms of a low white blood cell count are fevers, frequent infections which
can be severe, and flu-like illnesses that linger.
Too Few Platelets
People who do not have enough platelets tend to
bruise and bleed easily, and the bleeding may be hard to stop. Common types of
bleeding related to too few platelets include nosebleeds, bleeding gums,
pinpoint red bleeding spots on the skin, and blood in the stool. Women also may
have heavy menstrual bleeding.
Other Signs and Symptoms
Aplastic anemia can cause other signs and symptoms
as well. Some occur in the area of the head. These signs and symptoms include
headache, tender sinuses, and white patches in the mouth (oral thrush). Other
signs and symptoms are nausea and rash. A person with aplastic anemia also may
have an enlarged spleen or liver.
Paroxysmal Nocturnal Hemoglobinuria
About one-third of people with aplastic anemia have
a condition called paroxysmal (par-ok-SIZ-mal) nocturnal hemoglobinuria (PNH).
This is a disorder of the red blood cells. Most people with PNH dont have
any signs or symptoms. If they do occur, they may include:
- A low number of red blood cells, which can lead
to shortness of breath
- Swelling or pain in the abdomen or swelling in
the legs caused by blood clots
- Blood in the urine
- Headache
- Jaundice (yellowish color of the eyes or
skin)
Some people have PNH first and then develop aplastic
anemia. But this process can also happen in reverse. People may have aplastic
anemia first and then develop PNH later.
How Is Aplastic Anemia Diagnosed?
Aplastic anemia is diagnosed using a medical and
family history, a physical exam, and tests to discover the type and cause of
anemia. Your doctor can use these methods to find out how severe the anemia is
and to decide the appropriate treatment.
Specialists Involved
A person with suspected aplastic anemia may be
referred to a hematologist (an expert in treating blood conditions).
Medical and Family History
During a medical history, your doctor may ask
detailed questions about many kinds of symptoms. He or she may ask if you have
ever had problems with
anemia,
had an illness or condition that could cause anemia, or been exposed to drugs,
chemicals, or radiation. The doctor will ask about medicines you are taking to
see if they might be a cause of the anemia. The doctor will also ask if your
family members have ever had any kind of anemia.
Physical Exam
Your doctor will do a physical exam to see how
severe the anemia is and to check for its possible causes. This exam may
include:
- Checking for pale or yellowish skin
- Listening to the heart for rapid or irregular
heartbeats
- Listening to the lungs for rapid or uneven
breathing
- Feeling the abdomen to check the size of the
liver and spleen and checking for swelling in the legs
- Checking for signs of bleeding
Diagnostic Tests and Procedures
Several tests of the blood and bone marrow may be
used to diagnose aplastic anemia. The reasons for testing are to:
- Confirm a diagnosis of aplastic anemia and look
for its cause
- Rule out blood cancers that can cause bone marrow
failure
- Determine the severity of the aplastic
anemia
- Check for the presence of paroxysmal nocturnal
hemoglobinuria
Complete Blood Count
Usually, the first test used to diagnose anemia is a
complete blood count (CBC). The CBC tells a number of things about a
persons blood, including:
- The hemoglobin level. Hemoglobin is the iron-rich
protein in red blood cells that carries oxygen through the body. The normal
range of hemoglobin levels for the general population is 1115 g/dL. A low
hemoglobin level means a person has anemia.
- The hematocrit (hee-MAT-oh-crit) level. The
hematocrit level measures how much of the blood is made up of red blood cells.
The normal range for hematocrit levels for the general population is 3243
percent. A low hematocrit level is another sign of anemia.
The normal range of these levels may be lower in
certain racial and ethnic populations. Your doctor can explain your individual
test results.
The CBC also checks:
- The number of red blood cells. Too few red blood
cells means a person has anemia. A low number of red blood cells is usually
seen with either a low hemoglobin or a low hematocrit level, or both.
- The number of white blood cells. White blood
cells are involved in fighting infection.
- The number of platelets in the blood. Platelets
are small cell fragments that are involved in blood clotting.
- Red blood cell size. The mean cell volume
measures the average size (volume) of red blood cells.
Reticulocyte Count
This test measures the number of new red blood cells
in the blood. It helps doctors find out whether bone marrow is producing red
blood cells at the proper rate. A lower than average level can mean that the
bone marrow is not making enough red blood cells. The reticulocyte
(re-TIK-u-lo-site) level is low in people with aplastic anemia.
Bone Marrow Tests
This test looks at the bone marrow to see if it is
healthy and if it is making enough blood cells. A small amount of bone marrow
may be removed and examined. Removing a small bit of liquid bone marrow is
called aspiration. Removing bone marrow tissue is called biopsy.
A bone marrow aspiration may be done to find what is
causing the low production of blood cells. Since blood cells are formed inside
the bones, doctors use a needle to remove a small amount of liquid bone marrow.
The sample is then examined under a microscope to check for abnormal cells.
A bone marrow biopsy is usually done at the same
time, especially if an aspiration was not productive. A small number of bone
marrow cells with a small piece of bone is removed using a needle. This test
checks the number and type of cells in the bone marrow. In aplastic anemia, the
bone marrow has a lower than normal number of cells.
Other Tests
Additional tests may be used to help diagnose
aplastic anemia, including:
- X ray,
CT scan, or
ultrasound of the abdomen to look for an enlarged spleen or
lymph nodes, which could indicate blood cancer. These tests also may be used to
examine the kidneys, arms, and hands, which are sometimes abnormal in young
people with Fanconi anemia.
- Chest x ray to provide a picture of the heart and lungs and
rule out infection.
- Liver tests and viral studies to check for
hepatitis and viruses.
- Tests that check vitamin B12 and folate levels to
rule out anemia due to vitamin deficiency.
- Blood tests for paroxysmal nocturnal
hemoglobinuria and to check the immune system for antibodies.
How Is Aplastic Anemia Treated?
Treatments for aplastic anemia include:
- Blood transfusions
- Bone marrow transplants
- Several medicines used to suppress the immune
system, stimulate the bone marrow, and prevent and treat infections
In rare cases, no treatment is needed.
In general, treatments for aplastic anemia can limit
and prevent complications, relieve symptoms, and improve quality of life. For
some, a cure may be possible. Bone marrow transplants can be a cure for those
people who are eligible for a transplant. Removing a known cause of aplastic
anemia (such as exposure to a toxic chemical) also can cure the disorder. Other
treatments can restore blood cell counts to levels high enough so that a person
can live a normal life.
Who Needs Treatment
People with mild or moderate aplastic anemia may not
need treatment as long as the condition does not get worse. People with severe
aplastic anemia need immediate medical treatment to prevent complications from
the very low levels of blood cells in their bodies. People with very severe
aplastic anemia need emergency medical care and hospitalization or the anemia
can be fatal in a short time.
Blood Transfusions
Blood transfusions are used to keep blood counts
high enough in people with aplastic anemia. Healthy blood is taken from matched
donors and then given to the person with aplastic anemia through an injection
in a vein. Blood transfusions help relieve symptoms. They are not an effective
long-term treatment.
Red Blood Cells
Red blood cell transfusions help relieve lack of
energy, tiredness, and shortness of breath. However, if red blood cells are
given often, the immune system in the body can learn to recognize these new
cells, develop antibodies against them, and destroy these newly transfused
cells. Also, if red blood cells are given often, the body can build up too much
iron. Excess iron from transfusions can damage the heart, liver, and other
organs. If this happens, treatment may be needed to remove excess iron from the
body.
White Blood Cells
White blood cells are not routinely transfused
because they live in the bloodstream for less than 1 day. However, they may be
used for severe infections that are not being helped by antibiotics.
Platelets
Platelet transfusions reduce the risk of fatal
bleeding. Several transfusions a month are often needed because platelets live
only a few days. However, in time, the immune system will learn to recognize
and destroy newly transfused platelets by making antibodies, just as it does
with red blood cells.
Bone Marrow Transplantation
A bone marrow transplant replaces damaged stem cells
in bone marrow with healthy stem cells from a donors bone marrow. It is
the best treatment choice for eligible people because it usually cures aplastic
anemia.
A bone marrow transplant works best in children and
young adults with severe aplastic anemia who are in good health and who have
matched donors. Older people are less able to tolerate the treatments needed to
prepare the body for the transplant. They also are more likely to have
complications after the transplant. There are age limits for who can receive a
bone marrow transplant, but they vary among hospitals.
Finding a Donor
For best results, the donors bone marrow must
be a close match with the bone marrow of the person with aplastic anemia. A
matched donor is found by means of a blood test that looks at proteins on the
surface of body cells. These proteins are called human leukocyte antigens
(HLA). The donor and the person with aplastic anemia are both tested. The HLA
antigens on their cells are compared.
Bone marrow transplants work best if the donated
marrow is an exact match and comes from a family member, such as a brother or
sister. A person receiving bone marrow that is an exact match usually has fewer
complications. Only about 2035 percent of people with severe aplastic
anemia have an HLA-matched family member to donate bone marrow.
If no matching family member is found, the search
for bone marrow widens. Millions of volunteer donors are registered with the
National Marrow Donor Program. Doctors will look for:
- Donors who are HLA matches but are not family
members
- Family members who are not exact HLA matches
- Unrelated donors who are not exact HLA
matches
- Umbilical cord blood that is an HLA match
A person who is going to have a bone marrow
transplant should not receive blood transfusions from close family members
before the transplant. When a person receives blood transfusions, their bodies
can develop antibodies against the donated blood. If a person develops
antibodies against the blood of a close family member, the person would not be
able to receive a bone marrow transplant from that family member.
Receiving the Transplant
Bone marrow transplants are done in special units in
hospitals to try to protect the person with aplastic anemia from any
infections. Before the transplant, the person receives high doses of
chemotherapy, radiation therapy, or both. These treatments destroy the abnormal
bone marrow that is not producing blood cells.
A sample of bone marrow is taken from the donor and
is given to the recipient through a vein. The donated bone marrow stem cells
travel to the recipients bone marrow and start to make healthy blood
cells. If the transplant is successful, the new stem cells multiply and begin
making new, healthy blood cells within 3 to 4 weeks.
Possible Complications
After a bone marrow transplant, the recipient is in
the hospital for weeks or months. During this time, he or she is isolated and
closely watched for infections and other complications. Complications are most
likely to occur in the first 100 days after a transplant. Complications include
rejection of the graft and what is called graft-versus-host disease (GVHD).
Graft rejection. Sometimes, the
recipients immune system destroys the new bone marrow cells. This occurs
in 5 to 10 percent of recipients, and it is more likely to happen in people who
have had several bone marrow transplants.
GVHD. GVHD happens when the new
immune system cells, created by the donated bone marrow, attack the
recipients body. Signs and symptoms are skin inflammation, diarrhea, and
liver disease. GVHD can occur soon after transplant, or it can develop slowly
and can last for months or years. GVHD most often happens in older people and
those who receive unmatched transplants.
To help prevent GVHD, donor marrow is sometimes
treated or people may be given medicines that suppress the immune system after
the transplant. Those who develop mild but acute GVHD are treated with
medicines such as steroids.
Medicines To Stimulate Bone Marrow
Manmade versions of substances that occur naturally
in the body are used to stimulate the bone marrow to produce more blood cells.
Bone marrow that can produce more blood cells can help a person with aplastic
anemia avoid blood transfusions. An increased number of white cells can help
protect a person from infection. Examples of bone marrow stimulation medicines
used to treat aplastic anemia are:
- Erythropoietin (e-RITH-ro-PO-e-tin)
- Colony-stimulating factors
These medicines have some risks. Based on your
situation, you doctor will decide whether the benefits of the medicines
outweigh the risks.
Medicines To Suppress the Immune System
Since research suggests that aplastic anemia may
occur because the bodys immune system attacks its own cells by mistake,
certain medicines may be used to suppress the bodys immune system. They
allow the bone marrow to start making blood cells again, and they help avoid
the need for blood transfusions. Medicines that suppress the immune system do
not cure aplastic anemia, but they can relieve its symptoms and reduce its
complications.
These medicines are often used for people who are
not good candidates for a bone marrow transplant or who are waiting for a bone
marrow transplant.
There are three medicinesoften given
togetherthat will suppress the bodys immune system:
- Antithymocyte globulin (ATG)
- Cyclosporine
- Methylprednisolone (a corticosteroid)
If this treatment is successful, it may take a few
months to notice the effects of these medicines. Most often, as blood counts
rise, symptoms lessen. Blood counts in people who respond well to these drugs
do not usually reach normal levels, but they are often high enough to allow
people to take part in their normal activities. People with aplastic anemia may
need to take the medicines indefinitely to keep their blood counts high enough
to resume normal daily life.
Medicines that suppress the immune system can have
side effects. They also may increase the risk of developing leukemia
(loo-KE-me-a) or myelodysplasia (MI-e-lo-dis-PLA-ze-a; MDS). Leukemia is a type
of cancer in which the number of white blood cells increases. MDS is a
condition in which the bone marrow produces too many defective blood cells.
Antibiotics
Antibiotics and antivirals are given to people with
aplastic anemia to prevent and treat infections.
Living With Aplastic Anemia
Many people with aplastic anemia can be treated
successfully and some can be cured. Most people are able to resume their normal
activities after treatment. If you are being treated for aplastic anemia, it
may take a long time to get a good response from your treatment. You may need
repeated treatments, or you may need to try several treatments before finding
one that works.
Lifelong followup is needed to make sure the
disorder doesnt return, as well as to check for possible
complications.
Ongoing Health Care Needs
Treatment for aplastic anemia can result in side
effects or complications. Your doctor can talk with you about how to cope with
symptoms of aplastic anemia, side effects of treatment, and complications from
treatment.
Recommended Physical Activity
Your doctor might discuss what type and amount of
physical exercise may be helpful. For example, you may need to avoid activities
that cause chest pain or shortness of breath. You may want to stay away from
activities that could result in injuries and bleeding, such as contact
sports.
Protection From Infection
Your doctor also might discuss ways to reduce your
chance of getting an infection. These ways include staying away from people who
are ill, avoiding crowds, and avoiding certain kinds of foods that could expose
you to bacteria (for example, uncooked food can be a source of bacteria). You
may be advised to wash your hands thoroughly several times throughout the day
and to care for your teeth and gums to reduce the risk of infection in your
mouth or throat.
It is important to know the signs of infection, such
as a fever. Call your doctor at the first sign of an infection.
Support Groups
You or your family members may find it helpful to
know about resources that can give you emotional support as well as helpful
information about aplastic anemia and its treatment. Your doctor or hospital
social worker may have information about counseling and support services. They
also may be able to refer you to major support organizations that offer help
with financial planning, since treatment for aplastic anemia is expensive.
The
Aplastic Anemia & MDS International Foundation, Inc.
offers a variety of services and information, including:
- Emotional support through a toll-free hotline
(8007472820), e-mail, and numerous local support groups
- Educational materials and newsletters, including
some on their Web site
- Questions answered by people with aplastic anemia
and their family members
- Information on clinical trials and financial help
for travel expenses to take part in a clinical trial
- A patient registry
The
National Marrow Donor Program gives information and help to
bone marrow donors and recipients. This includes:
- Information and educational materials on the Web
site
- A toll-free information line
(8889996743) where you can speak with a case manager in the Office
of Patient Advocacy
- A donor registry
- A directory of major medical centers providing
transplant services
- Information on financial planning for bone marrow
transplant
Key Points
- Aplastic anemia is a rare and serious blood
disorder that happens when bone marrow stops making enough new blood
cells.
- Blood contains three types of cells: red blood
cells, white blood cells, and platelets.
- The hemoglobin in red blood cells carries
oxygen through your bloodstream to your bodys tissues and organs and
removes carbon dioxide (a waste product).
- White blood cells fight infection.
- Platelets help the blood to clot.
- In aplastic anemia, the numbers of all three
blood cell types are too low.
- The two main types of aplastic anemia are
acquired and hereditary. Acquired aplastic anemia can be caused by exposure to
toxic chemicals, radiation, certain medicines, or viruses. Hereditary aplastic
anemia occurs with certain inherited conditions, such as Fanconi anemia.
- Common signs and symptoms of aplastic anemia are:
- Low energy, tiredness, and weakness
- Bleeding that is hard to control
- Frequent fever or infections that linger
- Aplastic anemia is diagnosed using medical and
family history, a physical exam, and a number of tests and procedures.
- A complete blood count measures the number of
all types of blood cells.
- Bone marrow tests give important information
about the number and quality of bone marrow cells.
- Other tests may include studies of the
abdomen, chest, and liver.
- Treatments for aplastic anemia include blood
transfusions, bone marrow transplant, and medicines.
- Blood transfusions help with the immediate
problems of bone marrow failure but are not a permanent treatment.
- Bone marrow transplant can cure aplastic
anemia in some people.
- A number of medicines are used to treat
aplastic anemia. They can suppress the immune system, stimulate the bone
marrow, and treat infections.
- With appropriate treatment, many people with
aplastic anemia can be treated successfully and can live normal lives. Some
people with aplastic anemia can be cured with a bone marrow transplant.
Links to Other Information About Aplastic
Anemia
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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