Anemia
If you have anemia, people may say you have tired blood. That's because anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen to your tissues — can make you feel tired.
Many types of anemia exist, each with its own cause. The cause may be an iron or vitamin deficiency, blood loss, a chronic illness, or a genetic or acquired defect or disease. It may also be a side effect of a medication. Anemia can be temporary or long-term. It can range from mild to severe.
Anemia affects 3.4 million Americans, making it the most common blood disorder in the United States. Women and people with chronic diseases are at increased risk of the condition.
If you suspect you have anemia, see your doctor. Anemia can be a sign of serious illnesses, such as cancer or kidney disease. Treatments for anemia range from taking vitamin and iron supplements to undergoing medical procedures, such as blood transfusions or surgery. You may prevent some types of anemia by eating a healthy, varied diet.
The main symptom of most types of anemia is fatigue. Other signs and symptoms of anemia include:
- Weakness
- Pale skin, including decreased pinkness of your lips, gums, lining of your eyelids, nail beds
and palms
- A rapid heartbeat
- Shortness of breath
- Chest pain
- Dizziness
- Irritability
- Numbness or coldness in your hands and feet
- Headache
Initially, anemia can be so mild it goes unnoticed. But signs and symptoms increase as the condition progresses.
Blood consists of both a liquid called plasma and cells. Floating within the plasma are three types of blood cells:
- White blood cells. These blood cells fight infection.
- Platelets. These blood cells help your blood clot after a cut.
- Red blood cells (erythrocytes). These are the most abundant of the three types. They
carry oxygen from your lungs, via your bloodstream, to your brain and the other organs and tissues.
Your body needs a supply of oxygenated blood to function. Oxygenated blood helps give your body its
energy and your skin a healthy glow.
Red blood cells contain hemoglobin — a red, iron-rich protein that gives blood its red color. Hemoglobin enables red blood cells to carry oxygen from your lungs to all parts of your body, and to carry carbon dioxide waste from other parts of the body to the lungs so that it can be exhaled.
Most blood cells, including red blood cells, are produced regularly in your bone marrow — a red, spongy material found within the cavities of many of your large bones. To produce hemoglobin and red blood cells, your body needs iron and vitamins from the foods you eat.
Anemia is a state in which the number of red blood cells or the hemoglobin in them is below normal. When you're anemic, your body produces too few healthy red blood cells, loses too many of them or destroys them faster than they can be replaced. As a result, your blood is low on red blood cells to carry oxygen to your tissues — leaving you fatigued. Common types of anemia and their causes include:
- Iron deficiency anemia. This most common form of anemia affects 20 percent of women, 50
percent of pregnant women and 3 percent of men in the United States. The cause is a shortage of the
mineral iron in your body. Your bone marrow needs iron to make hemoglobin. Without adequate iron,
your body can't produce enough hemoglobin for red blood cells. The result is iron deficiency anemia.
One way your body gets iron is when blood cells die — the iron in them is recycled and used to
produce new blood cells. So, if you lose blood, you lose iron. Women with heavy periods who lose a
lot of blood each month during menstruation are at risk of iron deficiency anemia. Slow, chronic
blood loss from a source within the body — such as an ulcer, a colon polyp or even colon cancer —
also can lead to iron loss and iron deficiency anemia. Your body also gets iron from the foods you
eat. An iron-poor diet can lead to this anemia. In pregnant women, a growing fetus can deplete the
mother's store of iron, leading to iron deficiency anemia.
- Vitamin deficiency anemias. In addition to iron, your body needs folate and vitamin B-12
to produce sufficient numbers of healthy red blood cells. Dietary requirements of folate are much
greater than are those for vitamin B-12. A diet lacking in these and other key nutrients can cause
decreased red blood cell production. People who have an intestinal disorder that affects the
absorption of nutrients are prone to this type of anemia. Some people are unable to absorb vitamin
B-12 for a variety of reasons and develop vitamin B-12 deficiency anemia, which is also known as
pernicious anemia. Vitamin deficiency anemias fall into a group of anemias called megaloblastic
anemias, in which the bone marrow produces large, abnormal red blood cells called megaloblasts.
Vitamin deficiency anemias can be related to the use of certain medications, such as oral
contraceptives, antiseizure medications and drugs used to treat cancer.
- Anemia of chronic disease. Certain chronic diseases — such as AIDS, cancer, liver disease
and chronic inflammatory diseases, such as rheumatoid arthritis — can interfere with the production
of red blood cells, resulting in chronic anemia. Kidney failure also can be a cause of anemia. The
kidneys produce a hormone called erythropoietin, which stimulates your bone marrow to produce red
blood cells. A shortage of erythropoietin, which can result from kidney failure or be a side effect
of chemotherapy, can result in a shortage of red blood cells.
- Aplastic anemia. This is a life-threatening anemia caused by a decrease in the bone
marrow's ability to produce all three types of blood cells — red blood cells, white blood cells and
platelets. Often, the cause of aplastic anemia is unknown, but it's believed to be an autoimmune
disease. Some factors that can be responsible for this type of anemia include chemotherapy,
radiation therapy, environmental toxins, pregnancy and lupus.
- Anemias associated with bone marrow disease. A variety of diseases, such as leukemia and
myelodysplasia, can cause anemia by affecting blood production in the bone marrow. The effects of
these types of cancer and cancer-like disorders vary from a mild alteration in blood production to a
complete shutdown of the blood-making process. The aggressive (acute) form of leukemia can be fatal
because it causes such a dramatic drop in the production of blood cells. Myelodysplasia is a
preleukemic condition that can cause anemia. Additionally, other cancers of the blood or bone
marrow, such as multiple myeloma or lymphoma, can cause anemia.
- Hemolytic anemias. This group of anemias develops when red blood cells are destroyed
faster than bone marrow can replace them. Certain blood diseases can cause increased red blood cell
destruction. Autoimmune disorders can cause your body to produce antibodies to red blood cells,
destroying them prematurely. Certain medications, such as some antibiotics used to treat infections,
also can break down red blood cells. Hemolytic anemias may cause yellowing of the skin (jaundice)
and an enlarged spleen.
- Sickle cell anemia. This inherited and sometimes serious anemia, which affects mainly
people of African and Arabic descent, is caused by a defective form of hemoglobin that forces red
blood cells to assume an abnormal crescent (sickle) shape. These irregular-shaped red blood cells
die prematurely, resulting in a chronic shortage of red blood cells. Sickle-shaped red blood cells
also can block blood flow through small blood vessels in the body, producing other, often painful,
symptoms.
- Other anemias. There are several other, rarer forms of anemia, such as thalassemia and
anemias caused by defective hemoglobin.
Sometimes, no cause of anemia can be identified.
These factors place you at increased risk of anemia:
- Poor diet. Anyone — young or old — whose diet is consistently low in iron and vitamins,
especially folate, is at risk of anemia. Your body needs iron and vitamins to produce sufficient
numbers of red blood cells.
- Intestinal disorders. Having an intestinal disorder that affects the absorption of
nutrients in the small intestine — such as Crohn's disease or celiac disease — puts you at risk of
anemia. Surgical removal of or surgery to the parts of the small intestine where nutrients are
absorbed can lead to nutrient deficiencies and anemia.
- Menstruation. In general, women are at greater risk of iron deficiency anemia than are
men. That's because women lose blood — and with it, iron — each month during menstruation.
- Pregnancy. Pregnant women are at an increased risk of iron deficiency anemia because
their iron stores have to serve the increased blood volume of the mother as well as be a source of
hemoglobin for the growing fetus.
- Chronic conditions. For example, if you have cancer, kidney or liver failure, or another
chronic condition, you may be at risk of anemia of chronic disease. These conditions can lead to a
shortage of red blood cells. Slow, chronic blood loss from an ulcer or other source within the body
can deplete your body's store of iron, leading to iron deficiency anemia.
- Family history. If your family has a history of an inherited anemia, you also may be at
increased risk of the condition.
Certain infections, blood diseases and autoimmune disorders, exposure to toxic chemicals and the use of some medications can affect red blood cell production and lead to an anemia. Other people at risk of anemia are people with diabetes, people who are dependent on alcohol (alcohol interferes with the absorption of folic acid) and people who adhere to a strict vegetarian diet, who may not get enough iron or B-12 in their diets.
| When to seek medical advice |
See your doctor if you're feeling fatigued for unexplained reasons, especially if you're at risk of anemia. Some anemias, such as iron deficiency anemia, are common. But don't assume that if you're tired, you must be anemic. Fatigue has many causes beyond anemia.
Some people learn that their hemoglobin is low, which indicates anemia, when they go to donate blood. Low hemoglobin may be a temporary problem remedied by eating more iron-rich foods or taking a multivitamin containing iron. However, it may also be a warning sign of blood loss in your body that may be causing you to be deficient in iron. If you're told that you can't donate blood because of low hemoglobin, ask your doctor if you should be concerned.
If you have a family history of an inherited anemia, such as sickle cell anemia, talk to your doctor and possibly a genetic counselor about your risk and what risks you may pass on to your children.
Doctors diagnose anemia with the help of a medical history, a physical exam and blood tests, including a complete blood count (CBC). This blood test measures levels of red blood cells and hemoglobin in your blood. Some of your blood may also be drawn and examined under a microscope to study the size, shape and color of your red blood cells, which may indicate a diagnosis. For example, in iron deficiency anemia, red blood cells are smaller and paler in color than normal. In vitamin deficiency anemias, red blood cells are enlarged and fewer in number.
If you receive a diagnosis of anemia, your doctor may order additional tests to determine the underlying cause. For example, iron deficiency anemia can result from chronic bleeding of known or unknown ulcers, benign polyps in the colon, a colon cancer, or kidney or other types of tumors. Your doctor may test for these and other conditions that may underlie the anemia.
Occasionally, it may be necessary to study a sample of your bone marrow to diagnose anemia.
When anemia is severe enough, it may interfere with your ability to do everyday tasks. You may be too exhausted to work or play. Although anemia is often treatable, it may take several weeks to months for red blood cell levels to return to normal after treatment. Ask your doctor what to expect from treatment.
If you've received a diagnosis of anemia — it's often detected during routine blood exams — ask your doctor what treatment is necessary. Then be sure to follow through on treatment, even if you start to feel better. Left unchecked, anemia can lead to a rapid or irregular heartbeat — an arrhythmia. Your heart must pump more blood to compensate for the lack of oxygen in the blood when you're anemic. This can even lead to heart attack or stroke. Untreated pernicious anemia can lead to nerve damage and decreased mental function, as vitamin B-12 is important not only for healthy red blood cells but also for optimal nerve and brain function.
Some inherited anemias, such as sickle cell anemia, can be serious and lead to life-threatening complications. Losing a lot of blood quickly results in acute, severe anemia and can be fatal.
Treatment for anemia depends on the cause:
- Iron deficiency anemia. This form of anemia is treated with iron supplements, which you
may need to take for several months or longer. If the underlying cause of iron deficiency is loss of
blood — other than from menstruation — the source of the bleeding must be located and stopped. This
may involve surgery.
- Vitamin deficiency anemias. Pernicious anemia is treated with injections — often lifetime
injections — of vitamin B-12. Folic acid deficiency anemia is treated with folic acid supplements.
- Anemia of chronic disease. There's no specific treatment for this type of anemia. Doctors
focus on treating the underlying disease. Iron supplements and vitamins generally don't help this
type of anemia. However, if symptoms become severe, a blood transfusion or injections of synthetic
erythropoietin, a hormone normally produced by the kidneys, may help stimulate red blood cell
production and ease fatigue.
- Aplastic anemia. Treatment for this serious anemia may include blood transfusions to
boost levels of red blood cells. You may need a bone marrow transplant if your bone marrow is
diseased and can't make healthy blood cells. You may need immune-suppressing medications to dampen
your immune system's response and give the bone marrow a chance to start functioning again.
- Anemias associated with bone marrow disease. Treatment of these various diseases can
range from simple medication to chemotherapy to bone marrow transplantation. Treatment of these
types of anemia usually involves a consultation from a blood specialist (hematologist).
- Hemolytic anemia. Managing hemolytic anemias includes avoiding suspect medications,
treating related infections and taking drugs that suppress your immune system, which may be
attacking your red blood cells. Short courses of treatment with steroids or gamma globulin can help
suppress your immune system's attack on your red blood cells. If the condition has caused an
enlarged spleen, you may to have your spleen removed. The spleen — a small organ below your rib cage
on the left side — filters out and stores defective red blood cells. Certain hemolytic anemias can
cause the spleen to become enlarged with damaged red blood cells.
- Sickle cell anemia. Treatment for this incurable anemia may include the administration of
oxygen, pain-relieving drugs, and oral and intravenous fluids to reduce pain and prevent
complications. Doctors also commonly use blood transfusions, folic acid supplements and antibiotics.
A bone marrow transplant may be an effective treatment in some circumstances. A cancer drug called
hydroxyurea (Droxia, Hydrea) also is used to treat sickle cell anemia in adults.
With treatment, many anemias can be eliminated. Iron deficiency anemia should go away once iron stores are restored and any source of internal bleeding is stopped. Vitamin deficiency anemias often can be successfully treated with supplements. However, pernicious anemia will reoccur if vitamin B-12 injections are stopped. Anemia of chronic disease, aplastic anemia and hemolytic anemias can be managed if not corrected. Sickle cell anemia and other inherited anemias are incurable, but symptoms can be relieved with treatment.
Many types of anemia can't be prevented. However, you can help avoid iron deficiency anemia and vitamin deficiency anemias by eating a healthy, varied diet that includes foods rich in iron, folate and vitamin B-12.
The best sources of iron are beef, pork and lamb. Other foods rich in iron include beans and peas, iron-fortified cereals, whole-grain breads and pastas, dark green leafy vegetables, dried fruit, nuts and seeds. Folate, and its synthetic form, folic acid, can be found in citrus juices, fresh fruits and vegetables, meat, dairy products, fortified breakfast cereals and beans. Vitamin B-12 is plentiful in meat and dairy products. Foods containing vitamin C help increase iron absorption.
Eating plenty of iron-containing foods is particularly important for people who have high iron requirements, such as children — iron is needed during growth spurts — and pregnant and menstruating women. Adequate iron intake is also crucial for infants, strict vegetarians and long-distance runners.
Doctors may prescribe iron supplements or multivitamins containing iron for people with high iron requirements. But iron supplements are appropriate only when you need more iron than a balanced diet can provide. Don't assume that if you're tired that you simply need to take iron supplements. Overloading your body with iron can be dangerous.
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June 2, 2003 —
