What Is Anemia?
Anemia (uh-NEE-me-eh) is a condition in which your
blood has a lower than normal number of red blood cells. This condition also
can occur if your red blood cells don’t contain enough hemoglobin
(HEE-muh-glow-bin). Hemoglobin is an iron-rich protein that gives blood its red
color. This protein helps red blood cells carry oxygen from the lungs to the
rest of the body.
If you have anemia, your body doesn’t get
enough oxygen-rich blood. As a result, you may feel tired and have other
symptoms. With severe or long-lasting anemia, the lack of oxygen in the blood
can damage the heart, brain, and other organs of the body. Very severe anemia
may even cause death.
Overview
Red blood cells are disc-shaped and look like
doughnuts without holes in the center. They carry oxygen and remove carbon
dioxide (a waste product) from your body. These cells are made in the bone
marrow—a sponge-like tissue inside the bones. Red blood cells live for
about 120 days in the bloodstream and then die.
White blood cells and platelets (PLATE-lets) also
are made in the bone marrow. White blood cells help fight infection. Platelets
stick together to seal small cuts or breaks on the blood vessel walls and stop
bleeding. With some types of anemia, you may have low numbers of all three
types of blood cells.
Anemia has three main causes: blood loss, lack of
red blood cell production, or high rates of red blood cell destruction. These
causes may be due to a number of diseases, conditions, or other factors.
Outlook
Many types of anemia can be mild, short term, and
easily treated. Some types can even be prevented with a healthy diet. Other
types can be treated with dietary supplements.
However, certain types of anemia may be severe, long
lasting, and life threatening if not diagnosed and treated.
If you have signs and symptoms of anemia, you should
see your doctor to find out whether you have the condition. Treatment will
depend on what has caused the anemia and how severe it is.
Other Names for Anemia
- Iron-poor blood
- Low blood
- Tired blood
There are many types of anemia with specific causes
and traits. Some of these include:
What Causes Anemia?
The three main causes of anemia are:
- Blood loss
- Lack of red blood cell production
- High rates of red blood cell destruction
Some people have anemia due to more than one of
these factors.
Blood Loss
Blood loss is the most common cause of anemia,
especially
iron-deficiency
anemia. Blood loss can be short term or persist over time.
Heavy menstrual periods or bleeding in the digestive
or urinary tract can cause blood loss. Surgery, trauma, or cancer also can
cause blood loss.
If a lot of blood is lost, the body may lose enough
red blood cells to cause anemia.
Lack of Red Blood Cell Production
Both acquired and inherited conditions and factors
can prevent your body from making enough red blood cells.
“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.
Examples of acquired conditions and factors that can
prevent your body from making enough red blood cells include diet, hormones,
some chronic (ongoing) diseases, and pregnancy.
Aplastic
anemia also can prevent your body from making enough red blood cells. This
condition can be acquired or inherited.
Diet
A diet that lacks iron, folic acid (folate), or
vitamin B12 can prevent your body from making enough red blood cells. Your body
also needs small amounts of vitamin C, riboflavin, and copper to make red blood
cells.
Conditions that make it hard for your body to absorb
nutrients also can cause your body to make too few red blood cells.
Hormones
Your body needs the hormone erythropoietin
(eh-rith-ro-POY-eh-tin) to make red blood cells. This hormone stimulates the
bone marrow to make these cells. A low level of this hormone can lead to
anemia.
Diseases and Disease Treatments
Chronic (long-term) diseases, like kidney disease
and cancer, can make it hard for the body to make enough red blood cells.
Some cancer treatments may damage the bone marrow or
damage the red blood cells’ ability to carry oxygen. If the bone marrow is
damaged, it can’t make red blood cells fast enough to replace the ones
that died or were destroyed.
People who have HIV/AIDS may develop anemia due to
infections or medicines used to treat their diseases.
Pregnancy
Anemia can occur during pregnancy due to low levels
of iron and folic acid (folate) and changes in the blood.
During the first 6 months of pregnancy, the fluid
portion of a woman’s blood (the plasma) increases faster than the number
of red blood cells. This dilutes the blood and can lead to anemia.
Aplastic Anemia
Some infants are born without the ability to make
enough red blood cells. This condition is called aplastic anemia. Infants and
children who have aplastic anemia often need
blood
transfusions to increase the number of red blood cells in their blood.
Acquired conditions or factors, such as certain
medicines, toxins, and infectious diseases, also can cause aplastic anemia.
High Rates of Red Blood Cell Destruction
Both acquired and inherited conditions and factors
can cause your body to destroy too many red blood cells.
One example of an acquired condition that can cause
your body to destroy too many red blood cells is an enlarged or diseased
spleen. The spleen is an organ that removes worn-out red blood cells from the
body. If the spleen is enlarged or diseased, it may remove more red blood cells
than normal, causing anemia.
Examples of inherited conditions that can cause your
body to destroy too many red blood cells include
sickle
cell anemia,
thalassemias,
and lack of certain enzymes. These conditions create defects in the red blood
cells that cause them to die faster than healthy red blood cells.
Hemolytic
anemia is another example of a condition in which your body destroys too
many red blood cells. Inherited conditions can cause this type of anemia.
Acquired conditions or factors, such as immune disorders, infections, certain
medicines, or reactions to blood transfusions, also can cause hemolytic anemia.
Who Is At Risk for Anemia?
Populations Affected
Anemia is a common condition. It occurs in all age
groups and all racial and ethnic groups. Both men and women can have anemia,
but women of childbearing age are at higher risk for the condition. This is
because women in this age range lose blood from menstruation.
Anemia can develop during pregnancy due to low
levels of iron and folic acid (folate) and changes in the blood. During the
first 6 months of pregnancy, the fluid portion of a woman’s blood (the
plasma) increases faster than the number of red blood cells. This dilutes the
blood and can lead to anemia.
Infants younger than 2 years old also are at risk
for anemia. This is because they may not get enough iron in their diets,
especially if they drink a lot of cow's milk. Cow's milk is low in the iron
needed for growth. Drinking too much cow’s milk may keep an infant or
toddler from eating enough iron-rich foods. It also may keep his or her body
from absorbing iron from iron-rich food.
Researchers continue to study how anemia affects
older adults. More than 10 percent of older adults have mild forms of anemia.
Many of these people have other medical conditions as well.
Major Risk Factors
Factors that raise your risk for anemia include:
- A diet that is low in iron, vitamins, or
minerals
- Blood loss from surgery or an injury
- Long-term or serious illnesses, such as kidney
disease, cancer, diabetes, rheumatoid arthritis, HIV/AIDS, inflammatory bowel
disease (including Crohn’s disease), liver disease,
heart
failure, and thyroid disease
- Long-term infections
- A family history of inherited anemia, such as
sickle
cell anemia or
thalassemias
What Are the Signs and Symptoms of Anemia?
The most common symptom of anemia is fatigue
(feeling tired or weak). If you have anemia, it may seem hard to find the
energy to do normal activities.
Other signs and symptoms of anemia include:
- Shortness of breath
- Dizziness
- Headache
- Coldness in the hands and feet
- Pale skin
- Chest pain
These signs and symptoms can occur because your
heart has to work harder to pump more oxygen-rich blood through your body.
Mild to moderate anemia may cause very mild symptoms
or none at all.
Complications of Anemia
Some people who have anemia may have
arrhythmias
(ah-RITH-me-ahs). An arrhythmia is a problem with the rate or rhythm of the
heartbeat. Over time, arrhythmias can damage your heart and possibly lead to
heart
failure. Anemia also can damage other organs in your body because your
blood can’t get enough oxygen to them.
Anemia can weaken people who have cancer or
HIV/AIDS. This can make their treatments not work as well.
Anemia also can cause many other medical problems.
People who have kidney disease and anemia are more likely to have heart
problems. In some types of anemia, too little fluid intake or too much loss of
fluid in the blood and body can occur. Severe loss of fluid can be life
threatening.
How Is Anemia Diagnosed?
Your doctor will diagnose anemia based on your
medical and family histories, a physical exam, and results from tests and
procedures.
Because anemia doesn’t always cause symptoms,
your doctor may find out you have it while checking for another condition.
Medical and Family Histories
Your doctor may ask whether you have any of the
common signs or symptoms of anemia.
He or she may ask whether you’ve had an illness or condition that could
cause anemia.
Your doctor also may ask about the medicines you
take, your diet, and whether you have family members who have anemia or a
history of it.
Physical Exam
Your doctor will do a physical exam to find out how
severe your anemia is and to check for possible causes. He or she may:
- Listen to your heart for a rapid or irregular
heartbeat
- Listen to your lungs for rapid or uneven
breathing
- Feel your abdomen to check the size of your liver
and spleen
Your doctor also may do a pelvic or rectal exam to
check for common sources of blood loss.
Diagnostic Tests and Procedures
Your doctor may order various tests or procedures to
find out what type of anemia you have and how severe it is.
Complete Blood Count
Often, the first test used to diagnose anemia is a
complete
blood count (CBC). The CBC measures many different parts of your blood.
This test checks your hemoglobin and hematocrit
(hee-MAT-oh-crit) levels. Hemoglobin is the iron-rich protein in red blood
cells that 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 may be lower 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 anemia, a blood disorder, 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 and a clue as to the cause of your anemia. In
iron-deficiency
anemia, for example, red blood cells usually are smaller than normal.
Other Tests and Procedures
If the CBC results show that you have anemia, you
may need other tests such as:
- Hemoglobin electrophoresis (e-lek-tro-FOR-e-sis).
This test looks at the different types of hemoglobin in your blood. It can help
diagnose the type of anemia you have.
- A reticulocyte (re-TIK-u-lo-site) count. This
test 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.
- Tests for the level of iron in your blood and
body. These include serum iron and serum ferritin tests. Transferrin level and
total iron-binding capacity also test iron levels.
Because anemia has many causes, you also may be
tested for conditions such as kidney failure, lead poisoning (in children), and
vitamin deficiencies (lack of vitamins, such as B12 and folic acid).
If your doctor thinks that you have anemia due to
internal bleeding, he or she may suggest several tests to look for the source
of the bleeding. A test to check the stool for blood may be done in your
doctor’s office or at home. Your doctor can give you a kit to help you
get a sample at home. He or she will tell you to bring the sample back to the
office or send it to a lab.
If blood is found in the stool, other tests may be
used to find the source of the bleeding. One such test is endoscopy
(en-DOS-ko-pe). For this test, a tube with a tiny camera is used to view the
lining of the digestive tract.
Your doctor also may want to do
bone
marrow tests. These tests show whether your bone marrow is healthy and
making enough blood cells.
How Is Anemia Treated?
Treatment for anemia depends on the type, cause, and
severity of the condition. Treatments may include dietary changes or
supplements, medicines, or procedures.
Goals of Treatment
The goal of treatment is to increase the amount of
oxygen that your blood can carry. This is done by raising the red blood cell
count and/or hemoglobin level. Another goal is to treat the underlying
condition or cause of the anemia.
Dietary Changes and Supplements
Low levels of vitamins or iron in the body can cause
some types of anemia. These low levels may be due to poor diet or certain
diseases or conditions.
To raise your vitamin or iron levels, your doctor
may ask you to change your diet or take vitamin or iron supplements. Common
vitamin supplements are vitamin B12 and folic acid (folate). Vitamin C is
sometimes given to help the body absorb iron.
Iron
Your body needs iron to make hemoglobin. Your body
can more easily absorb iron from meats than from vegetables or other foods. To
treat your anemia, your doctor may suggest eating more meat—especially
red meat, such as beef or liver—as well as chicken, turkey, pork, fish,
and shellfish.
Nonmeat foods that are good sources of iron
include:
- Spinach and other dark green leafy
vegetables
- Peanuts, peanut butter, and almonds
- Eggs
- Peas; lentils; and white, red, and baked
beans
- Dried fruits, such as raisins, apricots, and
peaches
- Prune juice
Iron is added to some foods, such as cereal, bread,
and pasta. You can look at the Nutrition Facts label on a food to find out how
much iron it contains. The amount is given as a percentage of the total amount
of iron you need every day.
Iron can be given as a mineral supplement.
It’s usually combined with multivitamins and other minerals that help
your body absorb iron.
Vitamin B12
Low levels of vitamin B12 can lead to
pernicious
anemia. This type of anemia is often treated with vitamin B12
supplements.
Good food sources of vitamin B12 include:
- Breakfast cereals with added vitamin B12
- Meats such as beef, liver, poultry, fish, and
shellfish
- Egg and dairy products (such as milk, yogurt, and
cheese)
Folic Acid
Folic acid (folate) is a form of vitamin B
that’s found in foods. Your body needs folic acid to make and maintain
new cells. Folic acid also is very important for pregnant women. It helps them
avoid anemia and promotes healthy growth of the fetus.
Good sources of folic acid include:
- Bread, pasta, and rice with added folic acid
- Spinach and other dark green leafy
vegetables
- Black-eyed peas and dried beans
- Beef liver
- Eggs
- Bananas, oranges, orange juice, and some other
fruits and juices
Vitamin C
Vitamin C helps the body absorb iron. Good sources
of vitamin C are vegetables and fruits, especially citrus fruits. Citrus fruits
include oranges, grapefruits, tangerines, and similar fruits. Fresh and frozen
fruits, vegetables, and juices usually have more vitamin C than canned
ones.
If you’re taking medicines, ask your doctor or
pharmacist whether you can eat grapefruit or drink grapefruit juice. This fruit
can affect the strength of a few medicines and how well they work.
Other fruits rich in vitamin C include kiwi fruit,
mangos, apricots, strawberries, cantaloupes, and watermelons.
Vegetables rich in vitamin C include broccoli,
peppers, tomatoes, cabbage, potatoes, and leafy green vegetables like romaine
lettuce, turnip greens, and spinach.
Medicines
Your doctor may prescribe medicines to increase the
number of red blood cells your body makes or to treat an underlying cause of
anemia. Some of these medicines include:
- Antibiotics to treat infections.
- Hormones to treat adult and teenaged women who
have heavy menstrual bleeding.
- A man-made version of erythropoietin to stimulate
your body to make more red blood cells. This hormone has some risks. You and
your doctor will decide whether the benefits of this treatment outweigh the
risks.
- Medicines to prevent the body’s immune
system from destroying its own red blood cells.
- Chelation (ke-LAY-shun) therapy for lead
poisoning. Chelation therapy is used mainly in children. This is because
children who have iron-deficiency anemia are at increased risk for lead
poisoning.
Procedures
If your anemia is severe, you may need a medical
procedure to treat it. Procedures include blood transfusions and blood and
marrow stem cells transplants.
Blood Transfusion
A blood transfusion is a safe, 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.
For more information, see the Diseases and
Conditions Index
Blood
Transfusion article.
Blood and Marrow Stem Cell Transplant
A blood and marrow stem cell transplant replaces
your abnormal or faulty stem cells with healthy ones from another person (a
donor). Stem cells are found in the bone marrow. They develop into red and
white blood cells and platelets.
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.
For more information, see the Diseases and
Conditions Index
Blood
and Marrow Stem Cell Transplant article.
Surgery
If you have serious or life-threatening bleeding
that’s causing anemia, you may need surgery. For example, you may need
surgery to control ongoing bleeding due to a stomach ulcer or colon cancer.
If your body is destroying red blood cells at a high
rate, you may need to have your spleen removed. The spleen is an organ that
removes worn-out red blood cells from the body. An enlarged or diseased spleen
may remove more red blood cells than normal, causing anemia.
How Can Anemia Be Prevented?
You may be able to prevent repeat episodes of some
types of anemia, especially those caused by lack of iron or vitamins. Dietary
changes or supplements can prevent these types of anemia from occurring
again.
Treating the condition’s underlying cause may
prevent anemia (or prevent repeat episodes). For example, if your doctor finds
out that a medicine is causing your anemia, talk to him or her about other
medicine options.
To prevent your anemia from becoming more severe,
tell your doctor about all of your signs and symptoms. Discuss the tests you
may need with your doctor and follow your treatment plan.
You can’t prevent some types of inherited
anemia, such as
sickle
cell anemia. If you have an inherited anemia, talk to your doctor about
treatment and ongoing care.
Living With Anemia
Often, you can treat and control anemia. If you have
signs and symptoms of this condition, seek prompt diagnosis and treatment.
Treatment may give you a greater energy and activity level, improve your
quality of life, and help you live longer.
With proper treatment, many types of anemia are mild
and short term. However, anemia can be severe, long lasting, or even fatal when
it’s due to an inherited disease, chronic disease, or trauma.
Anemia and Children/Teens
Infants and young children have a greater need for
iron because of their rapid growth. Not enough iron can lead to anemia. Preterm
and low-birth-weight babies are often watched closely for anemia.
Most of the iron your child needs comes from food.
Talk to your child’s doctor about a healthy diet and good sources of
iron, vitamins B12 and C, and folic acid (folate). Only give your child iron
supplements if the doctor prescribes them. You should carefully follow
instructions on how to give your child these supplements.
If your child has anemia, his or her doctor may ask
whether the child has been exposed to lead. Lead poisoning in children has been
linked to
iron-deficiency
anemia.
Teenagers are at risk for anemia, especially
iron-deficiency anemia, because of their growth spurts. Routine screenings for
anemia are often started in the teen years.
Older children and teens who have certain types of
severe anemia may be at higher risk for injuries or infections. Talk to your
child’s doctor about whether your child needs to avoid high-risk
activities, such as contact sports.
Girls begin to menstruate and lose iron with each
monthly period. Some girls and women are at higher risk for anemia due to
excessive blood loss from menstruation or other causes, low iron intake, or a
history of anemia. These girls and women may need regular screenings and
followup for anemia.
Anemia and Pregnant/Postchildbirth Women
Anemia can occur during pregnancy due to lack of
iron and folate and changes in the blood. During the first 6 months of
pregnancy, the fluid portion of a woman’s blood (the plasma) increases
faster than the number of red blood cells. This dilutes the blood and can lead
to anemia.
Severe anemia raises the risk of having a preterm
birth or a low-birth-weight baby. Thus, pregnant women should be screened for
anemia during their first prenatal visits. They also need routine followup as
part of prenatal care.
Women often are tested for anemia after delivery
(postpartum), especially if they had:
- Anemia that continued during the last 3 months
(third trimester) of pregnancy
- A lot of blood loss during pregnancy, childbirth,
or after childbirth
- Multiple births
Anemia and Older Adults
Chronic diseases, lack of iron, and/or generally
poor nutrition often cause anemia in older adults. In this age group, anemia
often occurs with other medical problems. Thus, the signs and symptoms of
anemia often aren’t as clear and may be overlooked.
You should contact your doctor if you have any
signs or symptoms of anemia. If
you’re diagnosed with anemia, your doctor may:
- Ask about your diet to see whether you’re
getting enough vitamins. He or she may recommend vitamins or iron or folic acid
supplements.
- Prescribe a man-made version of erythropoietin if
your anemia is due to cancer, kidney disease, or treatments for these diseases.
Erythropoietin is a hormone that stimulates the bone marrow to make red blood
cells.
- Recommend a
blood
transfusion if your anemia is severe.
Key Points
- Anemia is a condition in which your blood has a
lower than normal number of red blood cells. This condition also can occur if
your red blood cells don’t contain enough hemoglobin. Without enough red
blood cells or hemoglobin, the blood doesn’t carry enough oxygen to the
body.
- The lack of oxygen causes people who have anemia
to feel tired and weak. With severe or long-lasting anemia, the lack of oxygen
in the blood can damage the heart, brain, and other organs in the body. Very
severe anemia may even cause death.
- Anemia has three main causes: blood loss, lack of
red blood cell production, or high rates of red blood cell destruction. These
causes may be due to a number of diseases, conditions, or other factors.
- Anemia is a common condition. It occurs in all
age groups and all racial and ethnic groups. Women and people who have chronic
diseases are at increased risk for anemia.
- The most common symptom of anemia is fatigue
(feeling tired or weak). Other signs and symptoms include shortness of breath,
dizziness, headache, coldness in the hands and feet, pale skin, and chest pain.
Mild to moderate anemia may cause mild symptoms or none at all.
- Your doctor will diagnose anemia based on your
medical and family histories, a physical exam, and results from tests and
procedures. Often, the first test use to diagnose anemia is a
complete
blood count (CBC). A CBC measures many different parts of your blood.
- Treatment for anemia depends on the type, cause,
and severity of the condition. Treatments may include dietary changes or
supplements, medicines, or procedures.
- You may be able to prevent repeat episodes of
some types of anemia by making dietary changes, taking supplements, or treating
an underlying condition.
- Often, you can treat and control anemia. If you
have signs and symptoms of this condition, seek prompt diagnosis and treatment.
With proper treatment, many types of anemia are mild and short term.
Links to Other Information About Anemia
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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