Iron Deficiency Anemia

Iron-deficiency anemia occurs when there is not enough iron in the body. This lack of iron in the body can be due to bleeding, not eating enough foods that contain iron, or not absorbing enough iron from food that is eaten.

In young children, iron-deficiency anemia can delay growth and development and cause heart murmurs. It puts a child at greater risk for lead poisoning and infections, and can also lead to behavior problems.

In pregnant women, in whom it is common, iron-deficiency anemia can increase the risk of a premature delivery and a low-birth-weight baby.

In all adults, iron-deficiency anemia can lead to various heart problems.

Iron-deficiency anemia is the most common type of anemia, and can usually be easily treated.

Other Names

• Iron-deficiency anaemia (British spelling)

Anemia

Anemia is a condition that affects the red blood cells (RBCs), or erythrocytes.

Red blood cells are disc-shaped and look like doughnuts with a dent instead of a hole in the center. The main role of RBCs is to carry oxygen, but they also remove carbon dioxide (a waste product) from cells and carry it to the lungs to be exhaled.

In anemia, either the blood contains fewer than the normal number of RBCs, or the RBCs do not have enough hemoglobin. Hemoglobin is an iron-containing protein that binds to oxygen. The RBCs carry oxygen-containing blood from the lungs into the rest of the body. In anemia, the blood doesn't carry enough oxygen in the body.

There are many kinds of anemia, but iron-deficiency anemia is the most common. (A lack of iron in the body is the most common nutritional problem.) It is most often found in young children, pregnant women, and women of childbearing age.

Signs and Symptoms

Signs and symptoms of anemia depend on how severe it is. 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 the same for all anemias.

Symptoms common to all types 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).

The heart is affected when there is a lack of oxygen in the body. Since the heart must work harder to move the reduced amount of oxygen, signs and symptoms may include shortness of breath and chest pain. Anemia can lead to a fast or irregular heartbeat, a heart murmur (especially in children), an enlarged heart, or heart failure.

When red blood cells do not have enough hemoglobin, common signs include pale skin, tongue, gums, and nail beds. Other signs and symptoms 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

Symptoms specific for iron-deficiency anemia

Symptoms of iron-deficiency anemia include unusual cravings for non-food items such as ice, paint, starch, or dirt. This type of craving is called pica.

Another symptom of iron-deficiency anemia is restless legs syndrome (RLS).^[1] 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, irritability, and a slower rate of growth and development.

Some of the 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. Bleeding from the gut cannot always be seen however, even if it is severe enough to cause anemia, and stools may appear to be completely normal.

Causes

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 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.

Iron-deficiency anemia develops after iron is lost from the body by one of the ways listed below. 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. Then, 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.

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.

Blood loss

When blood is lost, iron is lost. Iron-deficiency anemia usually is found in those with chronic blood loss. In acute (sudden) blood losses, such as hemorrhaging, the iron levels have not adjusted enough to be considered an iron-deficient state. But if the body does not have enough iron reserves to make up for the iron lost through bleeding, 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), which may cause bleeding in the stomach or intestine
• Hookworm infection
• Bleeding in the kidneys or bladder

A more rapid loss or removal of blood that can cause iron-deficiency anemia occurs in situations such as:

• Severe injuries
• Surgery
• Many blood tests done very frequently

In the case of severe injuries and surgery, the patient is suffering more from the loss of fluid volume than iron deficiency, and they will most likely be treated with IV fluids rather than iron.

Lack of iron in the diet

Meat, poultry, fish, eggs, and dairy products are the best sources of iron found in food. Some foods, such as breakfast cereals, are fortified with iron. Diets that exclude these foods or food supplements may lead to iron-deficiency anemia. For example, people limiting intake of animal foods, such as in vegetarian, low-fat, or high-sugar diets, may not eat enough foods with iron. Other people get iron-deficiency anemia because of eating poorly due to alcoholism or aging. High-fiber 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. Breastfed infants do get enough iron through breast milk, even if the mother is iron-deficient.^[2] The iron in human milk is very well-absorbed.^[3]

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

An increased need for iron

People need more iron during 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 is another 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.

Diagnosis

Iron-deficiency anemia is diagnosed using the following:

• Medical history, when the clinician talks to the patient and examines records
• Physical exam, including a hemoccult exam to look for microscopic blood in the stool
• Blood tests such as CBC, hemoglobin, and iron levels
• Procedures such as colonoscopy to look for a source of bleeding

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, emergency physicians, or internal medicine doctors. Other doctors may be consulted, such as experts on diseases of the blood (hematologists) or experts on diseases of the digestive system (gastroenterologists).

Exams and tests

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 with pelvic and rectal exams (these areas are common sources of blood loss)

Blood tests

A doctor may order various tests or procedures to determine the type and severity of anemia. 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 grams per deciliter (g/dL). A low hemoglobin level means a person has anemia.
• The hematocrit level. The hematocrit level, sometimes called the "crit," 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%. A low hematocrit level is another sign of anemia.

The normal range of these levels may be lower in certain racial and ethnic populations.

The CBC also checks:

• The number of RBCs (RBC count). A low RBC count 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.
• The mean cell volume, which 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 anemia, a doctor may order additional tests to determine the cause, severity, and correct treatment of the anemia. 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 the blood. The reticulocyte test is used to determine whether the bone marrow is producing red blood cells at the proper rate.

Tests for iron

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, called erythrocyte protoporphyrin.

Tests for gastrointestinal bleeding

If anemia is suspected because of internal bleeding in the stomach or intestines (gastrointestinal or GI bleeding), 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.
• 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.

Chances of Developing Iron Deficiency Anemia

Risk factors

The major risk factors for iron-deficiency anemia are slow, chronic 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. Between 10% and 20% of women of childbearing age has iron-deficiency anemia.^[4]

Pregnant women need twice as much iron in their diet than women who are not pregnant. If a pregnant woman does not get enough iron for herself and the growing baby, she can develop iron-deficiency anemia. Many pregnant women have this type of anemia, particularly late in pregnancy, but the exact percentage isn't known. It may be as high as 45% in minority women.^[5]

Young children

Infants and toddlers 6 to 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 four to six months of life. After that, infants need to get iron from food or supplements. Premature babies and babies of low-birth-weight 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

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, alcoholics, and older adults who have poor diets.

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.

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 emergency measures.

Treatment to stop bleeding

Treatment will depend on why the body is bleeding and where it is bleeding. Anemia cannot be cured until the bleeding is stopped.

Treatment to increase iron in the diet

A diet rich in iron, folic acid, and vitamin C is recommended 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. 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.

Prevention

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.

Infants and young children

Early signs of anemia can be detected in infants and young children by blood tests, 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% of the iron in breast milk but only about 12% 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 three 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 one 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 to 12 milligrams of iron.
• Babies older than four 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. Parents and caregivers should keep all iron supplements and vitamins away from children and ask for child-proof packages for supplements.

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 to 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.

Pregnant women

Many 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 typically includes screening for anemia.

The doctor giving prenatal care may prescribe iron supplements, which should be taken as directed. The doctor also may give advice on how to get higher levels of iron through eating iron-rich foods.

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.

Clinical Trials

For a list of government-sponsored clinical trials on anemia, visit this link.

References

1. ↑ Gamaldo CE, Earley CJ. Restless legs syndrome: a clinical update. Chest. 2006 Nov;130(5):1596-604. Abstract | Full Text
2. ↑ Raj S, Faridi M, Rusia U, Singh O. A prospective study of iron status in exclusively breastfed term infants up to 6 months of age. Int Breastfeed J. 2008 Mar 1;3:3. Abstract | Full Text
3. ↑ La Leche League International. The Womanly Art of Breastfeeding, 7th ed. (New York: Penguin Group, 2004), 346.
4. ↑ Centers for Disease Control and Prevention. Iron Deficiency --- United States, 1999--2000. MMWR Weekly Report. October 11, 2002. 51(40);897-899. Full Text
5. ↑ Scholl TO. Iron status during pregnancy: setting the stage for mother and infant. Am J Clin Nutr. 2005 May;81(5):1218S-1222S. Abstract | Full Text

External Links

Centers for Disease Control and Prevention:

• Nutrition Topics
• Morbidity and Mortality Weekly Report. “Recommendations to Prevent and Control Iron Deficiency in the United States. 1998 3 April. Vol 47. No RR-3.”