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iron-deficiency anemia





iron-deficiency anemia
Causes of 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. 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 (erythrocytes).

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 (see pregnancy), 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 (see nutrition). 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.


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.


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 624 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 46 months of life. After that, infants need to get iron from food or supplements. Premature and low-birthweight 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.


Outlook

Iron-deficiency anemia can be treated successfully. Depending on the level of iron deficiency, a doctor or healthcare practitioner may prescribe iron supplements. When taken correctly, iron supplements can help support, maintain and even restore healthy iron levels, reducing or eliminating iron deficiency anemia. 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 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.


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. 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 11.115.0 g/dL. A low hemoglobin level means a person has anemia.

  • The hematocrit 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 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 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.


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 912 months of age
  • Babies who are 1518 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 412 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 510 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 46 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)

Related category

   • HEALTH AND DISEASE

Source: U.S. National Heart, Lung and Blood Institute