What Is Iron-Deficiency Anemia?
Iron-deficiency anemia is a common and easily
treated condition that occurs when there is not enough iron in the body. It is
the most common type of anemia. A
lack of iron in the body can come from bleeding, not eating enough foods that
contain iron, or not absorbing enough iron from food that is eaten.
Anemia
The term "anemia" (uh-NEE-me-uh) is used for a group
of conditions in which the number of red blood cells in the blood is lower than
normal, or the red blood cells dont have enough hemoglobin
(HEE-muh-glow-bin). Hemoglobinan iron-rich protein that gives the red
color to bloodcarries the oxygen from the lungs to the rest of the body.
In people with anemia, the blood does not carry enough oxygen 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.
Red blood cells also are called RBCs or erythrocytes
(eh-RITH-roh-sites). Normal red blood cells are all about the same size and
look like doughnuts without a hole in the center. They are produced by the
spongy marrow inside the large bones of the body. Healthy red blood cells have
an average lifespan of 120 days. When they die, the iron from the hemoglobin is
recycled to make new red blood cells.
There are many types of anemia. The three major
causes of anemia are blood loss, decreased production of red blood cells, or
increased destruction of red blood cells. White blood cells and platelets are
the two other kinds of blood cells. White blood cells help fight infection.
Platelets help blood to clot. In some kinds of anemia, there are low amounts of
all three types of blood cells. The most common symptom of all types of anemia
is feeling tired because the body is not receiving enough oxygen.
Iron-Deficiency Anemia
In iron-deficiency anemia, the body does not have
enough iron to form hemoglobin, which means there is not enough hemoglobin to
carry oxygen to the whole body. The body gets its iron from food. The main
foods that contain iron are meat and shellfish as well as iron-fortified foods
(that is, foods that have iron added). A steady supply of iron is needed to
form hemoglobin and healthy red blood cells.
A person can have low iron levels for three
reasons:
- Blood loss, either from disease or injury
- Not getting enough iron in the diet
- Not being able to absorb the iron in the
diet
Iron-deficiency anemia also can develop when the
body needs higher levels of iron, such as during pregnancy.
Effects of Iron-Deficiency Anemia on the Body
Iron-deficiency anemia can range from mild to
severe. A mild case usually causes no symptoms or problems. However, a severe
case can cause extreme fatigue (tiredness) and weakness. Severe iron-deficiency
anemia can lead to serious problems for young children and pregnant women, and
it can affect the heart.
In young children, iron-deficiency anemia can cause
a
heart
murmur and delays in growth and development. It puts a child at greater
risk for lead poisoning and infections, and it can cause behavior problems.
In pregnant women, iron-deficiency anemia can
increase the risk of a premature delivery and a low-birth-weight baby.
The heart is affected when there is a lack of oxygen
in the body. The heart has to work harder to get enough oxygen throughout the
body. Over time, this stress on the heart can lead to a fast or irregular
heartbeat, chest pain, an enlarged heart, and even
heart
failure.
Important General Information
A lack of iron in the body is the most common
nutritional problem. Iron-deficiency anemia is the most common form of anemia.
It is most often found in young children, pregnant women, and women of
childbearing age. In fact, it affects half of all pregnant women and 1 out of 5
women of childbearing age.
Outlook
Iron-deficiency anemia can be treated successfully.
The causes of iron-deficiency anemia can most often be treated successfully as
well. However, if not treated, it can lead to severe symptoms and serious
problems.
What Causes Iron-Deficiency Anemia?
Iron-deficiency anemia occurs when there is too
little iron in the body. A person can have a low iron level for three reasons:
- Blood loss, either from disease or injury
- Not getting enough iron in the diet
- Not being able to absorb the iron in the
diet
Iron-deficiency anemia also can develop when the
body needs higher levels of iron, such as during pregnancy.
Loss of Iron Through Blood Loss
In general, when blood is lost, iron is lost. If the
body does not have enough iron reserves to make up for the iron loss, a person
will develop iron-deficiency anemia.
Blood is lost in a number of ways. In women, iron
and red blood cells are lost when bleeding occurs from very long or heavy
menstrual periods as well as from childbirth. Women also can lose iron and red
blood cells from slowly bleeding fibroids in the uterus.
Blood also is lost through internal bleeding. Most
often this loss of blood occurs slowly and can be due to:
- A bleeding ulcer, colon polyp, or colon
cancer
- Regular use of aspirin or other pain medicine
such as nonsteroidal anti-inflammatory drugs (for example, ibuprofen and
naproxen)
- Hookworm infection
- Urinary tract bleeding
A more rapid loss or removal of blood that can cause
iron-deficiency anemia occurs in situations such as:
- Severe injuries
- Surgery
- Frequent blood drawing
Lack of Iron in the Diet
Meat, poultry, fish, eggs, dairy products, or
iron-fortified foods (that is, foods that have iron added) are the best sources
of iron found in food. Eating patterns that exclude these foods or food
supplements may lead to iron-deficiency anemia. For example, some vegetarians
do not eat enough foods with iron. Other people get iron-deficiency anemia
because of eating poorly due to alcoholism or aging. Following a diet that has
an imbalance of food groups also can lead to this type of anemia. Examples of
diets that can lead to iron-deficiency anemia include:
- Low-fat diets. Following a low-fat diet over a
long period of time may limit sources of iron from animal foods.
- Diets high in sugars. These types of diets are
often low in iron.
- High-fiber diets. These types of diets can slow
the absorption of iron.
Infants who are fed cow's milk in the first year are
at risk for iron-deficiency anemia because cow's milk is low in iron. The same
is true for infants who are breastfed after 4 months of age. These infants need
iron supplements.
An Increased Need for Iron
People may need more iron at some periods in their
lives. If they do not get more iron at these times, they may develop
iron-deficiency anemia. Periods of rapid growth or growth spurts in children
and teens are a good example of an increased need for iron. Pregnancy also is
an example. The need for iron doubles during pregnancy due to an increased
blood volume, the growth of the fetus, and the blood loss that occurs during
childbirth.
Inability To Absorb Enough Iron From Food
Certain factors make it hard for the body to absorb
enough iron from food. These factors include:
- Intestinal surgery or diseases of the intestine,
such as Crohn's disease or celiac disease
- Prescription medicines that reduce acid in the
stomach
- Low levels of folate, vitamin B12, or vitamin C
in the diet
How Iron-Deficiency Anemia Develops
First, iron is lost from the body by one of the ways
listed above. Usually, this happens slowly over a period of time. Most often,
the person is not taking in enough iron to meet the needs of the body.
Next, the body starts to use iron that it has
stored. When the stored iron is used up, new red blood cells have less
hemoglobin than normal, and fewer red blood cells are produced. Finally, when
the number of red cells is too low, iron-deficiency anemia develops.
Who Is At Risk for Iron-Deficiency Anemia?
The major risk factors for iron-deficiency anemia
are blood loss and a diet low in iron. Three of the highest risk groups are
women, young children, and adults with intestinal bleeding.
Populations Affected
Women
Women who lose a lot of blood during their monthly
periods are at higher risk of developing iron-deficiency anemia. About 1 in 5
women of childbearing age has iron-deficiency anemia.
Pregnant women need twice as much iron in their diet
than women who are not pregnant. If a pregnant woman doesn't get enough iron
for herself and the growing baby, she can develop iron-deficiency anemia. About
half of all pregnant women have this type of anemia.
Young Children
Infants and toddlers 6-24 months of age need a lot
of iron to grow and develop. The iron that full-term infants have stored in
their bodies is used up in the first 4-6 months of life. After that, infants
need to get iron from food or supplements. Premature and low-birth-weight
babies are at even greater risk for iron-deficiency anemia because they don't
have as much iron stored in their bodies.
Other children at risk for anemia are:
- Children with poor nutrition, including
low-income children
- Children with lead in their blood
- Infants fed cow's milk before 1 year of age
- Breastfed infants older than 4 months who are not
receiving iron-rich solid foods or iron supplements
Adults With Intestinal Bleeding
Adults who bleed in their intestinal tract are at
risk for iron-deficiency anemia. This includes people who have bleeding ulcers
or colon cancer. It also includes people who use medicines that can cause
intestinal bleeding (for example, aspirin).
Other Adults
Other adults who are at risk for iron-deficiency
anemia include those who are on kidney dialysis, vegetarians, and older adults
who have poor diets.
What Are the Signs and Symptoms of Iron-Deficiency
Anemia?
Signs and symptoms of
anemia depend on the severity of the
condition. People with mild anemia or anemia that has come on very slowly may
have no symptoms at all. However, if the anemia is severe, the symptoms
increase and become more serious. Many of the signs and symptoms of
iron-deficiency anemia are true for all kinds of anemia.
Major Signs and Symptoms of Anemia
The major symptom of all types of anemia, including
iron-deficiency anemia, is fatigue (feeling tired). Fatigue is caused by having
too few red blood cells to carry oxygen to the body. This lack of oxygen in the
body can cause people to feel weak or dizzy, have a headache, or even pass out
when changing position (for example, standing up).
Since the heart must work harder to move the reduced
amount of oxygen, signs and symptoms may include shortness of breath and chest
pain. This can lead to a fast or irregular heartbeat or a
heart
murmur.
In anemia, the red blood cells don't have enough
hemoglobin. Common signs of lack of hemoglobin include pale skin, tongue, gums,
and nail beds.
Other Signs and Symptoms of Anemia
Other signs and symptoms of anemia can include:
- Cold hands and feet as well as brittle nails
- Swelling or soreness of the tongue and cracks in
the sides of the mouth
- An enlarged spleen
- Frequent infections
Signs and Symptoms of Iron-Deficiency Anemia
Symptoms of iron-deficiency anemia include unusual
cravings for nonfood items such as ice, dirt, paint, or starch. This craving
for nonfood items is called pica.
Another symptom of iron-deficiency anemia is
developing
restless
legs syndrome (RLS). RLS is a disorder that causes an uncomfortable feeling
in the legs that can only be relieved by movement. Sleep is difficult for
people with RLS.
In infants and young children, signs and symptoms
include a poor appetite, being irritable, and a slower rate of growth and
development.
Some of the signs and symptoms of iron-deficiency
anemia are related to its causes, such as blood loss. Blood loss is most often
seen with very heavy or long lasting menstrual bleeding or vaginal bleeding in
women after menopause. Other signs of internal bleeding are bright red blood in
the stool or black, tarry-looking stools.
How Is Iron-Deficiency Anemia Diagnosed?
Iron-deficiency anemia is diagnosed using a person's
medical history, a physical exam, and diagnostic tests and procedures. A doctor
can use these methods to determine how severe the anemia is, its cause, and
appropriate treatment. Mild to moderate anemia may have no signs or symptoms.
In fact, anemia is often discovered unexpectedly on screening tests and when
doctors are checking for other problems.
Specialists Involved
Primary care doctors often diagnose and treat
iron-deficiency anemia. These doctors include pediatricians, family doctors,
obstetricians, or internal medicine specialists. Other doctors may be
consulted, such as experts on diseases of the blood (hematologists) or experts
on diseases of the digestive system (gastroenterologists).
Medical and Family History
To find the cause of the anemia and how severe it
is, the doctor may ask detailed questions about symptoms (see the
What Are the Signs and Symptoms of
Iron-Deficiency Anemia? section). The doctor may ask whether the person or
a family member has ever had problems with
anemia. The doctor will ask about
things that may cause anemia, including illnesses, conditions (such as
pregnancy), and medicines. The doctor also may ask about the person's diet and
eating habits.
Physical Exam
A physical exam may include:
- Checking for pale or yellowish skin, gums, or
nail beds
- Listening to the heart for a rapid or irregular
heartbeat
- Listening to the lungs for rapid or uneven
breathing
- Feeling the abdomen to check the size of the
liver and spleen
- Checking for signs of bleeding, including a
pelvic and rectal exam (these areas are common sources of blood loss)
The doctor also will order a number of tests or
procedures to be sure about the type of anemia and how severe it is.
Diagnostic Tests and Procedures
Your doctor may order various tests or procedures to
determine the type and severity of anemia you have. Usually, the first test
used to diagnose anemia is a complete blood count (CBC). The CBC tells a number
of things about a person's 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 11.1-15.0 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 32-43
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 numbers 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 numbers of white blood cells. White blood
cells are involved in fighting infection.
- The number of platelets in the blood. Platelets
are small cells that are involved in blood clotting.
- Red blood cell size. The mean cell volume
measures the average size (volume) of red blood cells. In iron-deficiency
anemia, the red blood cells are often smaller than normal.
If the CBC results confirm that you have anemia,
your doctor may order additional tests to determine the cause, severity, and
correct treatment for your condition. For example, the doctor may order a
reticulocyte (re-TIK-u-lo-site) count. Reticulocytes are young red blood cells.
This test measures the number of new red blood cells in your blood. The
reticulocyte test is used to determine whether your bone marrow is producing
red blood cells at the proper rate.
Tests That Measure Iron Levels in the Body
Iron is needed to make hemoglobin-the protein in red
blood cells that gives them their color and carries oxygen. Several tests can
be used to check the level of iron in the blood and in the body:
- Serum iron. This test measures the amount of iron
in the blood. The level of iron in the blood can be normal even when the total
amount of iron in the body is low. For this reason, other iron tests are
done.
- Serum ferritin. Ferritin is a protein that helps
store iron in the body. Results of this test give doctors a good idea of how
much of the body's stored iron has been used up.
- Transferrin level or total iron-binding capacity.
Transferrin is a protein that carries iron in the blood. Total iron-binding
capacity measures how much of the transferrin in the blood is not carrying
iron. People with iron-deficiency anemia have a high level of transferrin that
has no iron.
- Other blood tests. Other tests the doctor may
order include tests that check hormone levels, especially the thyroid hormone.
Blood tests also may be ordered to check the level of a chemical used by the
body to make hemoglobin. It is called erythrocyte protoporphyrin.
Tests That Diagnose Gastrointestinal Bleeding
If your doctor suspects anemia because of internal
bleeding in the stomach or intestines, several tests may be used to discover
the source of the bleeding.
One of the first tests ordered is the fecal occult
blood test. This test checks the stool for signs of blood. It can detect even
small amounts of bleeding anywhere in the intestines. If blood is found in the
stool, further tests may be used to find the source of the bleeding,
including:
- Colonoscopy. In this test, a thin, flexible tube
attached to a video camera is used to examine the rectum and colon for sources
of bleeding.
- Upper GI endoscopy. In this test, a thin,
flexible tube attached to a video camera is used to examine the stomach and
upper intestines. The doctor looks for signs of bleeding.
- Pelvic ultrasound. This test uses sound waves to
look at the uterus and other pelvic organs. It checks for causes of heavy
vaginal bleeding, such as fibroids.
How Is Iron-Deficiency Anemia Treated?
Goals of Treatment
The goals of treating iron-deficiency anemia are to
restore normal levels of red blood cells, hemoglobin, and iron as well as to
treat the condition causing the anemia.
Specific Types of Treatment
Treatment for iron-deficiency anemia is based on the
cause and the severity of the condition. It will include treatment to stop any
bleeding, as well as changes in diet and iron supplements as needed. Severe
anemia may require more emergency measures.
Treatment To Stop Bleeding
Treatment will depend on why the body is bleeding
and where it is bleeding. Anemia will not improve until the bleeding is
stopped.
Treatment To Increase Iron in the Diet
Your doctor may recommend a diet rich in iron, folic
acid, and vitamin C to treat the anemia. Iron in meats is more easily absorbed
by the body than iron in vegetables and other foods. The best source of iron is
red meat, especially beef and liver. Chicken, turkey, pork, fish, and shellfish
also are good sources of iron.
Other foods high in iron are:
- Eggs
- Cereals, breads, or pastas that are fortified
with iron
- Beans and nuts, including peanut butter, almonds,
peas, lentils, and white, red, and baked beans
- Dried fruits (for example, raisins, apricots, and
peaches), prune juice
- Vegetables such as spinach and other dark green,
leafy vegetables
- Iron-fortified infant formula and cereals
Sources of vitamin C in foods include many fruits
and vegetables such as:
- Citrus fruits (for example, oranges, grapefruits,
and lemons) and their juices
- Kiwi fruit, mangos, apricots, strawberries,
cantaloupes, and watermelons
- Broccoli, peppers, tomatoes, cabbage, potatoes,
and leafy greens (for example, romaine lettuce, turnip greens, spinach)
The doctor may prescribe supplements to treat
anemia. Supplements can correct low iron levels within months if taken as
ordered. They include iron supplements in pill form and vitamin C to help the
body absorb the iron. Iron supplements also come in drops for children. But
iron supplements are very dangerous if taken in overdose, so it is important to
keep them away from children.
Iron and vitamin C supplements can cause side
effects, including dark stools and stomach irritation or heart burn. Iron also
can cause constipation, and a stool softener may be needed.
Treatment for Severe and Life-Threatening
Anemia
Severe anemia may need to be treated with
hospitalization, blood transfusions, and iron injections.
How Can Iron-Deficiency Anemia Be Prevented?
Eating a well-balanced diet rich in iron and
vitamins can help prevent iron-deficiency anemia. Red meat is the best source
of iron, but other meats, including poultry and seafood, are good sources of
iron as well. Besides meat, foods high in iron are:
- Eggs
- Cereals, breads, or pastas that are fortified
with iron
- Beans and nuts, including peanut butter, almonds,
peas, lentils, and white, red, and baked beans
- Dried fruits (for example, raisins, apricots, and
peaches), prune juice
- Vegetables such as spinach and other dark green,
leafy vegetables
- Iron-fortified infant formula and cereals
Food fads and dieting can sometimes lead to iron
deficiency. Weight loss diets that stress low-fat foods can mean that a person
will avoid animal foods that are good sources of iron. High-fiber diets can
make it hard for iron to be absorbed. High-sugar diets are often low in
iron.
Adults who eat a balanced diet usually don't need
iron supplements. However, people who don't absorb iron well and those who are
strict vegetarians may need them.
The Office of Dietary Supplements, National
Institutes of Health provides a
"Dietary Supplement Fact Sheet: Iron." This fact sheet
includes lists of food that are high in iron and the amount of iron provided by
a serving.
Preventing Anemia in Infants and Young
Children
Anemia can be prevented in infants and young
children by testing, especially in the following three age groups:
- Premature and low-birth-weight babies less than 6
months of age
- Babies who are 9-12 months of age
- Babies who are 15-18 months of age
Infants absorb iron best from breast milk. They can
absorb more than 50 percent of the iron in breast milk but only about 12
percent of the iron in infant formula.
Doctors usually recommend not giving cow's milk to
babies for the first year. Cow's milk is low in iron. The doctor may suggest
limiting cow's milk for children up to age 3 to no more than 24 ounces a
day-about three full baby bottles each day. A child who is drinking a lot of
milk may not be eating other foods that are better sources of iron. Drinking a
lot of milk also can lead to bleeding in the intestines.
Babies need more iron as they grow and begin to eat
solid foods. To help them get enough iron:
- Infants under age 1 who are not breastfed or who
are partially breastfed can be given iron-fortified infant formula. Iron
fortified means that each liter of formula has 4-12 milligrams of iron.
- Babies older than 4 months can be given iron-rich
or iron-fortified solid foods such as cereal.
The child's doctor can give advice on the best diet
for the infant. The doctor may recommend iron drops if the child needs an iron
supplement. Giving a child too much iron can be dangerous, so it is important
to be careful and follow the doctor's instructions. Parents and caregivers
should keep all iron supplements and vitamins away from children. They should
ask for child-proof packages for supplements.
Preventing Anemia in Adolescents and Women of
Childbearing Age
Teenaged girls and women of childbearing age are at
higher risk for iron-deficiency anemia due to blood loss from menstrual
bleeding. They should be tested for anemia every 5-10 years starting in their
teens. Girls and women at higher risk for anemia should be checked yearly. This
includes women who have a history of anemia, do not eat foods high in iron, or
have heavy blood loss from menstruation or other causes.
Preventing Anemia in Pregnant Women
Half of all pregnant women develop iron-deficiency
anemia because their volume of blood increases and because the growing fetus
needs iron. Anemia during pregnancy can lead to an increased risk of premature
delivery and a low-birth-weight baby.
To prevent these problems, pregnant women need twice
as much iron as women who are not pregnant. Pregnant women can get more iron
from eating more iron-rich foods, from supplements, or from both. Medical care
during pregnancy should include screening for anemia.
The doctor giving prenatal care may prescribe iron
supplements, which should be taken as directed. Pregnant women should notify
their doctors if they have uncomfortable side effects such as constipation. The
doctor also may give advice on how to get higher levels of iron through eating
iron-rich foods.
Preventing Anemia in Older Adults
Older adults may be at risk for iron deficiency due
to poor diet or illnesses that reduce iron absorption. Iron deficiency can take
away their sense of well-being, strength, and activeness. It also can make
symptoms of other conditions worse. Doctors can advise older adults about
eating iron-rich foods and how to use iron supplements to prevent
iron-deficiency anemia.
Living With Iron-Deficiency Anemia
If you have iron-deficiency anemia, you need to see
a doctor for treatment but you can recover, feel well, and live a normal
life.
Ongoing Health Care Needs
You will need regular medical checkups to make sure
your iron levels are going up. At your checkups you may have changes made to
your medicines or supplements, or you may get further advice on a healthy
diet.
During treatment for anemia, you may feel fatigue
(tiredness) and have other symptoms until your iron levels return to normal.
This can take months. Tell your doctor if you get any new symptoms or if your
symptoms get worse.
Take iron supplements only with your doctor's
approval. Don't decide to take them on your own. It is possible to get too high
a level of iron in your body and cause a condition called iron overload.
A pregnant woman with iron-deficiency anemia is
usually tested for anemia at 4-6 weeks after delivery, if she:
- Was anemic during the third trimester of
pregnancy
- Lost a lot of blood during childbirth
- Had a multiple birth (such as twins)
Key Points
- Iron-deficiency anemia is an illness that occurs
when there is not enough iron in the body.
- Iron helps the body make hemoglobin and healthy
red blood cells. Hemoglobin is needed to carry oxygen throughout the body.
- A person can have low iron levels for three
reasons: blood loss, either from disease or injury; not getting enough iron in
the diet; and not being able to absorb the iron in the diet. Iron-deficiency
anemia also can develop when the body needs higher levels of iron, such as
during pregnancy.
- One in five women of childbearing age and half of
all pregnant women have iron-deficiency anemia.
- Infants and toddlers can be at risk for
iron-deficiency anemia.
- The most common symptoms of iron-deficiency
anemia are fatigue (tiredness) and weakness.
- Iron-deficiency anemia is treated by stopping the
bleeding (if the cause of the anemia is bleeding), increasing iron in the diet,
and giving iron supplements.
- Eating a well-balanced diet rich in iron and
vitamins can help prevent iron deficiency anemia.
- Iron-deficiency anemia can be successfully
treated.
Links to Other Information About Iron-Deficiency
Anemia
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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