Iron Deficiency Anemia

In this condition factsheet:

• The Facts
• Causes
• Symptoms and Complications
• Making the Diagnosis
• Treatment and Prevention

The Facts

The blood that circulates throughout the body performs a number of critical functions. It delivers oxygen, removes carbon dioxide, and carries life-sustaining nutrients. By transporting long-distance messengers such as hormones, blood helps the various parts of the body communicate with each other. This is carried out by blood cells, working in partnership with the liquid part of the blood (plasma). Most of the cells that make up your blood are red blood cells (erythrocytes). White blood cells (leukocytes) are also present, defending the body against foreign material, including infections, viruses, and fungi.

Anemia occurs when there isn't enough hemoglobin (an iron-protein compound in red blood cells that transports oxygen) in the blood and there are too few red blood cells.

Anemias are the most common blood disorder; there are several types of anemia. They are usually caused by an iron deficiency. Approximately 3% of Canadians have anemia (including all forms of anemia). However, 9% of women aged 20 to 49, and 13% of women aged 12 to 19 have iron-deficiency.

Some infants may need extra iron, especially if they are bottle-fed with cow's milk. This is why doctors often prescribe iron supplements during infancy and why infant diets are iron-fortified and only iron-fortified formulas should be used.

Causes

Iron deficiency occurs when the body needs more iron than it's getting. The body needs the iron to make hemoglobin. Except in cases of malnourished infants, iron deficiency is almost always caused by long-term blood loss due to factors such as heavy menstrual periods, peptic ulcer disease, long-term aspirin use, colon cancer, uterine cancer, and malignancies (cancerous tumors). It may also occur if there's not enough iron-containing food in the person's diet or if there's poor absorption of iron (such as in the case of people who have celiac disease or have had gastric bypass surgery). Iron in the diet is absorbed more easily if it's heme iron, which is the form found in meat.

This form of anemia occurs quite often in pre-menopausal women because women lose blood during menstruation. Pregnant women who don't take iron supplements may develop iron deficiency anemia because their iron stores are used as a source of hemoglobin for the baby.

If infants, children, or adolescents have rapid growth spurts, they may get iron deficiency anemia. Lead poisoning can also lead to this condition in children. In persons over 50, lesions or injuries to the gastrointestinal tract, especially the colon, may result in chronic blood loss leading to anemia.

Symptoms and Complications

The symptoms of iron deficiency anemia appear gradually and may not be noticed.

The major symptom is fatigue. Many people, however, are unaware of just how tired they were until after they've been treated

In addition to feeling tired and having less energy, the person may have pale skin, gums, nail beds, and eyelid linings. Eventually, if anemia becomes severe enough, the heartbeat may become more rapid and noticeable.

Other symptoms of iron deficiency anemias may include:

• irritability
• weakness
• shortness of breath
• low blood pressure (especially when going from lying or sitting to standing)
• sore tongue
• brittle nails
• unusual food cravings (called pica) such as for ice or dirt
• decreased appetite (especially in children)
• headache

If it isn't treated, iron deficiency anemia may become severe enough to interfere with daily life. Infants with anemia who are not treated can develop growth and learning difficulties.

The good news is that its effects can be dealt with quickly by iron therapy. However, it's still important to find out the cause, because it may be a signal for a more serious disorder.

There are usually no complications from this anemia, but it may come back, so regular follow-ups with a doctor are needed. Children with this disorder may be more likely to get infections.

Making the Diagnosis

There are many ways to test for iron-deficiency anemia. Currently, the most reliable test is the serum ferritin assay. This test measures the amount of ferritin, a major iron storage protein, and reflects the amount of iron stored in your body. People are typically considered iron-deficient when ferritin levels drop below 15 µg/L for adults and 12 µg/L for children.

The serum ferritin assay isn't a perfect test; some (although not many) iron-deficient people have normal results. They're able to catch both false-positives and false-negatives in most situations.

The ferritin can be misleadingly high if there is inflammation, and so this test may not reflect low iron stores in people with chronic disorders, such as rheumatoid arthritis, chronic infection, or malignancies. In liver injuries and hepatitis, the serum ferritin concentration is often much higher.

Additional tests may be used to diagnose iron deficiency anemia. Common results are:

• low hematocrit (proportion of whole blood that is made up of red blood cells)
• low hemoglobin in a complete blood count
• saturation of transferrin (a protein that carries iron in the bloodstream)
• higher than normal TIBC (total iron binding capacity) levels
• blood loss (detected in a test of the stool for hidden blood loss)
• abnormal patterns in bone marrow iron staining (only used when other tests cannot definitively diagnose or rule out iron deficiency)

In some people, although the number of their individual red blood cells may be normal, the size may be diminished. Because iron deficiency may be a symptom of other serious conditions, it's essential that the cause be identified.

Treatment and Prevention

Treatment of iron deficiency anemia has two goals:

• to remove the cause of blood loss if possible (if this is the cause of the anemia)
• to cure the anemia by correcting iron deficiency

Both of these goals should be addressed at the same time, and treatment can start before the exact cause of the iron deficiency anemia is known.

Iron deficiency anemia often can't be treated by diet alone. In many cases, it wouldn't be possible for a person to eat enough iron-rich food in order to get the amount of iron needed. To help with bringing the iron levels back to normal, oral iron supplements are often prescribed. Injections are only necessary in severe cases, or when oral supplementation is not suitable for the underlying problem (e.g., as a result of poor absorption that often occurs after bariatric or gastric bypass procedures). It's still important, of course, for those on iron supplements to eat a proper, well-balanced diet.

Although expensive forms of iron supplements are available, iron replacement therapy generally doesn't cost more than a few dollars a month. Generally, the body cannot absorb more than 25 mg of elemental iron, so taking more than that will only increase the risk of side effects. Even though enteric-coated or prolonged-release iron supplements are available, iron pills shouldn't be enteric-coated or taken with meals or antacids, as this can reduce the amount of iron absorbed. Take iron pills between meals, and do not take them with milk, calcium, tea, offee, or  some medications (such as tetracycline), as this may also decrease absorption. Taking them with vitamin C can help absorption, but check with your doctor before trying this.

Seniors may respond more slowly to iron replacement therapy, and young people more rapidly. It's best to continue taking iron supplements for an additional 6 months after the cause is treated.

If only the anemia is treated, it's likely to come back. For this reason, it's important to find and treat the cause of the anemia.

All good oral iron preparations will cause stools to appear black. This is normal and doesn't mean there's blood loss. Although it's rare for iron supplements to cause problems, a few people may get abdominal discomfort, constipation, or loose stools from taking oral iron medications. Those whose symptoms continue may have to switch to a different form of iron (e.g., from ferrous sulfate to ferrous fumarate), reduce the dose of iron, or reduce the number of pills they take for a few days.

In severe cases of iron deficiency, or when oral iron isn't tolerated, iron may be given intravenously.

Blood transfusions are rarely performed to treat iron deficiency, except possibly in elderly persons with brain, heart, or kidney problems. Treatment of the underlying reason for the iron deficiency will be necessary for the iron to work. Otherwise, the iron is being lost as it is being replaced.

The key to prevention of iron deficiency anemia that's not due to disease or blood loss is proper nutrition. Plenty of iron-rich and easily absorbed foods such as meats (especially liver), fish, poultry, eggs, legumes (peas and beans), potatoes, and rice should be eaten. Iron is also absorbed more easily by the body if iron supplements and iron-rich foods are taken with citrus juice. Good eating habits are especially important for children, pregnant women, and women who are still menstruating. People who are strict vegetarians or on low-calorie diets should be aware of the symptoms of iron deficiency, as they may not be getting enough iron in their diets.

It's extremely important that breast-fed babies start receiving iron supplement drops or iron-fortified cereal after they are 6 months old.

Iron supplements can be helpful during growth spurts in children and in pregnancy. Too much iron, however, can cause liver damage and cirrhosis.

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