What Is Thrombocytopenia?
Thrombocytopenia (THROM-bo-si-to-PE-ne-ah) is a
condition in which your blood has a low number of blood cell fragments called
platelets (PLATE-lets).
Platelets are made in your bone marrow along with
other kinds of blood cells. They travel through your blood vessels and stick
together (clot) to stop any bleeding that could happen if a blood vessel is
damaged. Platelets also are called thrombocytes (THROM-bo-sites), because a
clot also is called a thrombus.
Overview
When your blood has a low number of platelets, mild
to serious bleeding can occur. This bleeding can happen inside the body
(internal bleeding) or on the skin.
A normal platelet count is 150,000 to 450,000
platelets per microliter of blood. A count of less than 150,000 platelets per
microliter is lower than normal. But the risk for serious bleeding doesn't
occur until the count becomes very lowless than 10,000 or 20,000
platelets per microliter. Milder bleeding sometimes occurs when the count
is less than 50,000 platelets per microliter.
Several factors can cause a low platelet count, such
as:
- The body's bone marrow doesn't make enough
platelets.
- The bone marrow makes enough platelets, but the
body destroys them or uses them up.
- The spleen holds onto too many platelets.
The spleen is an organ that normally stores about one-third of the body's
platelets. It also helps your body fight infection and remove unwanted cell
material.
- A combination of the above factors.
How long thrombocytopenia lasts depends on its
cause. It can range from days to years.
The treatment for this condition also depends on its
cause and severity. Mild thrombocytopenia most often doesn't need treatment. If
the condition is causing serious bleeding, or if you're at risk for serious
bleeding, you may need medicines or
blood
or platelet transfusions. Rarely, the spleen may need to be removed.
Outlook
Thrombocytopenia can be fatal, especially if the
bleeding is severe or occurs in the brain. However, the overall outlook is
good, especially if the cause of the low platelet count is found and
treated.
What Causes Thrombocytopenia?
A number of factors can cause thrombocytopenia (a
low platelet count). The condition can be inherited (passed from parents to
children), or it can develop at any age. Sometimes the cause isn't known.
In general, a low platelet count occurs
because:
- The body's bone marrow doesn't make enough
platelets.
- The bone marrow makes enough platelets, but the
body destroys them or uses them up.
- The spleen holds onto too many platelets.
A combination of the above factors also may cause a
low platelet count.
The Bone Marrow Doesn't Make Enough Platelets
Bone marrow is the sponge-like tissue inside the
bones. It contains stem cells that develop into red blood cells, white blood
cells, and platelets. When stem cells are damaged, they don't grow into healthy
blood cells.
Several conditions or factors can damage stem cells.
Cancer
Cancer, such as leukemia (lu-KE-me-ah) or lymphoma
(lim-FO-ma), can damage the bone marrow and destroy blood stem cells.
Cancer treatments, such as radiation and chemotherapy, also destroy the
stem cells.
Aplastic Anemia
Aplastic
anemia is a rare, serious blood disorder in which the bone marrow stops
making enough new blood cells. This lowers the number of platelets in
your blood.
Toxic Chemicals
Exposure to toxic chemicals, such as pesticides,
arsenic, and benzene, can slow the production of platelets.
Medicines
Some medicines, such as diuretics and
chloramphenicol, can slow the production of platelets. Chloramphenicol (an
antibiotic) is rarely used in the United States.
Common over-the-counter medicines, such as aspirin
or ibuprofen, also can affect platelets.
Alcohol
Alcohol also slows the production of platelets. A
temporary drop in platelets is common among heavy drinkers, especially if
they're eating foods that are low in iron, vitamin B12, or folate.
Viruses
Chickenpox, mumps, rubella, Epstein-Barr virus, or
parvovirus can decrease your platelet count for a while. People who have AIDS
often develop thrombocytopenia.
Genetic Conditions
Some genetic conditions, such as Wiskott-Aldrich and
May-Hegglin syndromes, can cause low numbers of platelets in the blood.
The Body Destroys Its Own Platelets
A low platelet count can occur even if the bone
marrow makes enough platelets. The body may destroy its own platelets due to
autoimmune diseases, certain medicines, infections, surgery, pregnancy, and
some conditions that cause too much blood clotting.
Autoimmune Diseases
With autoimmune diseases, the body's immune system
destroys its own platelets. One example of this type of disease is called
idiopathic
thrombocytopenic purpura, or ITP.
In most cases, the body's immune system is thought
to cause ITP. Normally, your immune system helps your body fight off
infections and diseases. But if you have ITP, your immune system attacks and
destroys its own plateletsfor an unknown reason.
Other autoimmune diseases that destroy platelets
include lupus and rheumatoid arthritis.
Medicines
A reaction to some medicines can confuse your body
and cause it to destroy its platelets. Any medicine can cause this reaction,
but it happens most often with quinine, antibiotics that contain sulfa, and
some medicines for seizures, such as Dilantin,® vancomycin, and
rifampin.
Heparin is a medicine commonly used to prevent blood
clots. But an immune reaction may trigger the medicine to cause blood
clots and thrombocytopenia. This condition is called heparin-induced
thrombocytopenia (HIT). HIT rarely occurs outside of a hospital.
In HIT, the body's immune system attacks a substance
formed by heparin and a protein on the surface of the platelets. This attack
activates the platelets and they start to form blood clots. Blood clots can
form deep in
the legs, or a clot can break loose and
travel
to the lungs.
Infection
A low platelet count can occur after blood poisoning
from a widespread bacterial infection. A virus, such as mononucleosis or
cytomegalovirus, also can cause a low platelet count.
Surgery
Platelets can be destroyed when they pass through
man-made heart valves, blood vessel grafts, or machines and tubing used for
blood
transfusions or
bypass
surgery.
Pregnancy
About 5 percent of pregnant women develop mild
thrombocytopenia when they're close to delivery. The exact cause isn't known
for sure.
Rare and Serious Conditions That Cause Blood
Clots
Some diseases can cause a low platelet count. Two
examples are
thrombotic
thrombocytopenic purpura (TTP) and disseminated intravascular clotting
(DIC).
TTP is a rare blood condition. It causes blood clots
to form in the body's small blood vessels, including vessels in the brains,
kidneys, and heart.
DIC is a rare complication of pregnancy, severe
infections, or severe trauma. Tiny blood clots form suddenly throughout
the body.
In both conditions, the blood clots use up many of
the blood's platelets.
The Spleen Holds On to Too Many Platelets
Usually, one-third of the body's platelets are held
in the spleen. If the spleen is enlarged, it will hold on to too many
platelets. This means that not enough platelets will circulate in the blood.
An enlarged spleen is often due to severe liver
diseasesuch as cirrhosis (sir-RO-sis) or cancer. Cirrhosis is a disease
in which the liver is scarred. This prevents it from working properly.
An enlarged spleen also may be due to a bone marrow
condition, such as myelofibrosis (MI-eh-lo-fi-BRO-sis). With this condition,
the bone marrow is scarred and isn't able to make blood cells.
Who Is At Risk for Thrombocytopenia?
People who are at highest risk for thrombocytopenia
are those affected by one of the conditions or factors discussed in
"What Causes Thrombocytopenia?" This includes
people who have:
- Certain types of cancer,
aplastic
anemia, or autoimmune diseases
- Been exposed to certain toxic chemicals
- A reaction to certain medicines
- Certain viruses
- Certain genetic conditions
People at highest risk also include heavy alcohol
drinkers and pregnant women.
What Are the Signs and Symptoms of
Thrombocytopenia?
Mild to serious bleeding causes the main signs and
symptoms of thrombocytopenia. Bleeding can occur inside the body (internal
bleeding) or on the skin.
Signs and symptoms can appear suddenly or over time.
Mild thrombocytopenia often has no signs or symptoms. Many times, it's
found during a routine
blood
test.
Check with your doctor if you have any signs of
bleeding. Severe thrombocytopenia can cause bleeding in almost any part of the
body. This can lead to a medical emergency and should be treated right away.
Bleeding on the skin is usually the first sign of a
low platelet count. This may appear as:
- Small red or purple spots on the skin called
petechiae (pe-TEE-key-ay). These spots often occur on the lower legs.
- Purple, brown, and red bruises called purpura.
Bruising may happen easily and often.
- Prolonged bleeding, even from minor cuts.
- Bleeding or oozing from the mouth or nose,
especially nosebleeds or bleeding from brushing your teeth.
A bleeding problem also can appear as abnormal
vaginal bleeding (especially heavy menstrual flow). A lot of bleeding after
surgery or dental work also may mean you have a bleeding problem.
Heavy bleeding into the intestines or the brain is
serious and can be fatal. Signs and symptoms include:
- Blood in the urine or stool or bleeding from the
rectum. Blood in the stool can appear as red blood or as a dark, tarry color.
(Taking iron supplements also can cause dark, tarry stools.)
- Headaches and other neurological symptoms. These
are very rare, but you should discuss them with your doctor.
How Is Thrombocytopenia Diagnosed?
Your doctor will diagnose thrombocytopenia based on
your medical history, a physical exam, and test results. A hematologist
also may be involved in your care. This is a doctor who treats blood
diseases.
Once thrombocytopenia is diagnosed, your doctor will
begin looking for its cause.
Medical History
Your doctor may ask you about factors that can
affect your platelets, such as:
- The medicines you take, including
over-the-counter medicines and herbal remedies, and whether you drink beverages
that contain quinine
- Your general eating habits, including the amount
of alcohol you normally drink
- Your risk for AIDS, including questions about
blood
transfusions, sexual partners, intravenous (IV) drugs, and exposure to
infectious blood or bodily fluids at work
- Any family history of low platelet counts
Physical Exam
Your doctor will do a physical exam to look for
signs and symptoms of bleeding, such as bruises or spots on the skin. He or she
will check your abdomen for signs of an enlarged spleen or liver. You also will
be checked for signs of infection, such as a fever.
Diagnostic Tests
Your doctor may order one or more of the following
tests to help diagnose a low platelet count. For more information on blood
tests, see the Diseases and Conditions Index
Blood
Tests article.
Complete Blood Count
A complete blood count (CBC) measures the levels of
red blood cells, white blood cells, and platelets in your blood. For this test,
a small amount of blood is drawn from a blood vessel, usually in your arm.
If you have thrombocytopenia, the results of this
test will show that your platelet count is low.
Blood Smear
A blood smear is used to check the appearance of
your platelets under a microscope. For this test, a small amount of blood is
drawn from a blood vessel, usually in your arm.
Bone Marrow Tests
Bone
marrow tests check whether your bone marrow is healthy. Blood cells,
including platelets, are made in bone marrow. The two bone marrow tests
are aspiration (as-pi-RA-shun) and biopsy.
Bone marrow aspiration may be done to find out why
your bone marrow isn't making enough blood cells. For this test, your doctor
removes a small amount of fluid bone marrow through a needle. He or she
examines the sample under a microscope to check for abnormal cells.
A bone marrow biopsy often is done right after an
aspiration. For this test, your doctor removes a small amount of bone
marrow tissue through a needle. Your doctor examines the tissue to check the
number and types of cells in the bone marrow.
Other Tests
If a bleeding problem is suspected, you may need
other blood tests as well. For example, tests called PT and PTT may be done to
see whether your blood is clotting properly.
Your doctor may order an ultrasound to check your
spleen. An ultrasound uses sound waves to create pictures of your spleen. This
will allow your doctor to see whether your spleen is enlarged.
How Is Thrombocytopenia Treated?
Treatment for thrombocytopenia depends on its cause
and how severe the condition is. The primary goal of treatment is to prevent
death and disability caused by bleeding.
If your condition is mild, you may not need
treatment. Your doctor should reassure you that a fully normal platelet count
isn't necessary to prevent bleeding, even with severe cuts or accidents.
Thrombocytopenia often improves when its underlying
cause is treated. People who inherit the condition usually don't need
treatment.
If a reaction to medicine is causing a low platelet
count, your doctor may prescribe other medicine. Most people recover after the
offending medicine has been stopped. For heparin-induced thrombocytopenia
(HIT), stopping the heparin isn't enough. Often, you'll need another medicine
to prevent blood clotting.
If your immune system is causing a low platelet
count, your doctor may prescribe medicines to suppress the immune system. When
the condition is severe, treatments may include:
- Medicines. You may be given steroids. This
medicine can be given through a vein or by mouth. One example of this type of
medicine is prednisone. You also may be given immunoglobulin. This medicine is
given through a vein.
-
Blood
or platelet transfusions. This type of treatment is reserved for people who
have active bleeding or are at a high risk for bleeding.
- Splenectomy. This is surgery to remove the
spleen. This treatment is most often used for adults who have
idiopathic
thrombocytopenic purpura.
How Can Thrombocytopenia Be Prevented?
Whether you can prevent thrombocytopenia depends on
its specific cause. Most cases of the condition can't be prevented. However,
you can take steps to prevent its complications.
- Avoid heavy drinking. Alcohol slows the
production of platelets.
- Avoid medicines that have decreased your
platelet count in the past.
- Be aware of medicines that may affect your
platelets and raise your risk for bleeding. Two examples of such medicines are
aspirin and ibuprofen. These medicines may thin your blood too much.
- Talk with your doctor about getting vaccinated
for viruses that can affect your platelets. You may need vaccines for mumps,
measles, rubella, and chickenpox. You may want to have your child
vaccinated for these viruses as well. Talk to you child's doctor about these
vaccines.
Living With Thrombocytopenia
If you have thrombocytopenia, watch for any
signs and symptoms of bleeding. Report these
signs and symptoms to your doctor right away.
Symptoms can appear suddenly or over time. Severe
thrombocytopenia can cause bleeding in almost any part of the body. This can
lead to a medical emergency and should be treated right away.
You can take steps to avoid complications of
thrombocytopenia. Watch what medicines you take, avoid injury, and contact your
doctor if you have fever or other signs or symptoms of an infection.
Medicines
Avoid medicines that may affect your platelets and
raise your risk for bleeding. Two examples of such medicines are aspirin and
ibuprofen. These medicines may thin your blood too much. Be careful when using
over-the-counter medicines, because many contain aspirin or ibuprofen.
Tell your doctor about all of the medicines you
take, including over-the-counter medicines, vitamins, supplements, and herbal
remedies.
Injury
Avoid injuries that can cause bruising and bleeding.
Don't participate in contact sports such as boxing, football, or karate. These
sports are likely to lead to injuries that can cause bleeding.
Other sports, such as skiing or horseback riding,
also put you at risk for injuries that can cause bleeding. Ask your
doctor about physical activities that are safe for you.
Take safety precautions, such as using seatbelts and
wearing gloves when working with knives and other tools.
If your child has thrombocytopenia, try to protect
him or her from injuries, especially head injuries that can cause bleeding in
the brain. Ask your child's doctor whether you need to restrict your
child's activities.
Infection
If you've had your spleen removed, you may be more
likely to become ill from certain types of infection. Watch for fever or other
signs and symptoms of infection and report them to your doctor promptly.
People who have had their spleens removed may need vaccinations to
prevent these infections.
Key Points
- Thrombocytopenia is a condition in which your
blood has a low number of blood cell fragments called platelets. Platelets
travel through your blood vessels and stick together (clot) to stop any
bleeding that could happen if a blood vessel is damaged.
- When the blood has a low number of platelets,
mild to serious bleeding can occur. This bleeding can happen inside the body
(internal bleeding) or on the skin.
- A normal platelet count is 150,000 to 450,000
platelets per microliter of blood. A count of less than 150,000 platelets per
microliter is lower than normal. However, the risk for serious bleeding doesn't
occur until the count becomes very lowless than 10,000 or 20,000
platelets per microliter. Milder bleeding sometimes occurs when the count is
less than 50,000 platelets per microliter.
- In general, a low platelet count develops for
one or more of these reasons:
- The body's bone marrow doesn't make enough
platelets.
- The bone marrow makes enough platelets, but
the body destroys them or uses them up.
- The spleen holds on to too many platelets.
The spleen is an organ that helps your body fight infection and remove unwanted
cell material.
- Mild to serious bleeding causes the main signs
and symptoms of thrombocytopenia. Signs and symptoms can appear suddenly or
over time. Mild thrombocytopenia often has no signs or symptoms.
- Your doctor will diagnose thrombocytopenia based
on your medical history, a physical exam, and tests results.
- Treatment for thrombocytopenia depends on its
cause and how severe the condition is. Thrombocytopenia often is improved by
treating its underlying cause. For severe cases, medicines,
blood
or platelet transfusions, or splenectomy (removal of the spleen) may be
needed.
- Most cases of thrombocytopenia can't be
prevented. However, you can take steps to avoid its complications. Avoid
drinking alcohol. Avoid medicines that have decreased your platelet count in
the past. Be aware of medicines that may affect your platelets and raise your
risk for bleeding. Talk with your doctor about getting vaccinated for
viruses that can affect your platelets.
- If you have thrombocytopenia, watch for
signs and symptoms of bleeding. Report these
signs and symptoms to your doctor right away. Watch what medicines you take,
avoid injury, and contact your doctor if you have a fever or other signs and
symptoms of an infection.
- Thrombocytopenia can be life threatening,
particularly if the bleeding is severe or occurs in the brain. However, the
overall outlook is good, especially if the cause of the low platelet count is
found and treated.
Links to Other Information About Thrombocytopenia
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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