Anemia (uh-NEE-me-eh) is a condition in which your blood has a lower than normal number of red blood cells. This condition also can occur if your red blood cells don’t contain enough hemoglobin (HEE-muh-glow-bin). Hemoglobin is an iron-rich protein that gives blood its red color. This protein helps red blood cells carry oxygen from the lungs to the rest of the body.
If you have anemia, your body doesn’t get enough oxygen-rich blood. As a result, you may feel tired and have other symptoms. With severe or long-lasting anemia, the lack of oxygen in the blood can damage the heart, brain, and other organs of the body. Very severe anemia may even cause death.
Red blood cells are disc-shaped and look like doughnuts without holes in the center. They carry oxygen and remove carbon dioxide (a waste product) from your body. These cells are made in the bone marrow—a sponge-like tissue inside the bones. Red blood cells live for about 120 days in the bloodstream and then die.
White blood cells and platelets (PLATE-lets) also are made in the bone marrow. White blood cells help fight infection. Platelets stick together to seal small cuts or breaks on the blood vessel walls and stop bleeding. With some types of anemia, you may have low numbers of all three types of blood cells.
Anemia has three main causes: blood loss, lack of red blood cell production, or high rates of red blood cell destruction. These causes may be due to a number of diseases, conditions, or other factors.
Many types of anemia can be mild, short term, and easily treated. Some types can even be prevented with a healthy diet. Other types can be treated with dietary supplements.
However, certain types of anemia may be severe, long lasting, and life threatening if not diagnosed and treated.
If you have signs and symptoms of anemia, you should see your doctor to find out whether you have the condition. Treatment will depend on what has caused the anemia and how severe it is.
What Causes Anemia?
The three main causes of anemia are:
- Blood loss
- Lack of red blood cell production
- High rates of red blood cell destruction
Some people have anemia due to more than one of these factors.
Blood loss is the most common cause of anemia, especially iron-deficiency anemia. Blood loss can be short term or persist over time.
Heavy menstrual periods or bleeding in the digestive or urinary tract can cause blood loss. Surgery, trauma, or cancer also can cause blood loss.
If a lot of blood is lost, the body may lose enough red blood cells to cause anemia.
Lack of Red Blood Cell Production
Both acquired and inherited conditions and factors can prevent your body from making enough red blood cells. “Acquired” means you aren’t born with the condition, but you develop it. “Inherited” means your parents passed the gene for the condition on to you.
Examples of acquired conditions and factors that can prevent your body from making enough red blood cells include diet, hormones, some chronic (ongoing) diseases, and pregnancy.
Aplastic anemia also can prevent your body from making enough red blood cells. This condition can be acquired or inherited.
A diet that lacks iron, folic acid (folate), or vitamin B12 can prevent your body from making enough red blood cells. Your body also needs small amounts of vitamin C, riboflavin, and copper to make red blood cells.
Conditions that make it hard for your body to absorb nutrients also can cause your body to make too few red blood cells.
Your body needs the hormone erythropoietin (eh-rith-ro-POY-eh-tin) to make red blood cells. This hormone stimulates the bone marrow to make these cells. A low level of this hormone can lead to anemia.
Diseases and Disease Treatments
Chronic (long-term) diseases, like kidney disease and cancer, can make it hard for the body to make enough red blood cells.
Some cancer treatments may damage the bone marrow or damage the red blood cells’ ability to carry oxygen. If the bone marrow is damaged, it can’t make red blood cells fast enough to replace the ones that died or were destroyed.
People who have HIV/AIDS may develop anemia due to infections or medicines used to treat their diseases.
Anemia can occur during pregnancy due to low levels of iron and folic acid (folate) and changes in the blood.
During the first 6 months of pregnancy, the fluid portion of a woman’s blood (the plasma) increases faster than the number of red blood cells. This dilutes the blood and can lead to anemia.
Some infants are born without the ability to make enough red blood cells. This condition is called aplastic anemia. Infants and children who have aplastic anemia often need blood transfusions to increase the number of red blood cells in their blood.
Acquired conditions or factors, such as certain medicines, toxins, and infectious diseases, also can cause aplastic anemia.
High Rates of Red Blood Cell Destruction
Both acquired and inherited conditions and factors can cause your body to destroy too many red blood cells.
One example of an acquired condition that can cause your body to destroy too many red blood cells is an enlarged or diseased spleen. The spleen is an organ that removes worn-out red blood cells from the body. If the spleen is enlarged or diseased, it may remove more red blood cells than normal, causing anemia.
Examples of inherited conditions that can cause your body to destroy too many red blood cells include sickle cell anemia, thalassemias, and lack of certain enzymes. These conditions create defects in the red blood cells that cause them to die faster than healthy red blood cells.
Hemolytic anemia is another example of a condition in which your body destroys too many red blood cells. Inherited conditions can cause this type of anemia. Acquired conditions or factors, such as immune disorders, infections, certain medicines, or reactions to blood transfusions, also can cause hemolytic anemia.
Who Is At Risk for Anemia?
Anemia is a common condition. It occurs in all age groups and all racial and ethnic groups. Both men and women can have anemia, but women of childbearing age are at higher risk for the condition. This is because women in this age range lose blood from menstruation.
Anemia can develop during pregnancy due to low levels of iron and folic acid (folate) and changes in the blood. During the first 6 months of pregnancy, the fluid portion of a woman’s blood (the plasma) increases faster than the number of red blood cells. This dilutes the blood and can lead to anemia.
Infants younger than 2 years old also are at risk for anemia. This is because they may not get enough iron in their diets, especially if they drink a lot of cow's milk. Cow's milk is low in the iron needed for growth. Drinking too much cow’s milk may keep an infant or toddler from eating enough iron-rich foods. It also may keep his or her body from absorbing iron from iron-rich food.
Researchers continue to study how anemia affects older adults. More than 10 percent of older adults have mild forms of anemia. Many of these people have other medical conditions as well.
Major Risk Factors
Factors that raise your risk for anemia include:
- A diet that is low in iron, vitamins, or minerals
- Blood loss from surgery or an injury
- Long-term or serious illnesses, such as kidney disease, cancer, diabetes, rheumatoid arthritis, HIV/AIDS, inflammatory bowel disease (including Crohn’s disease), liver disease, heart failure, and thyroid disease
- Long-term infections
- A family history of inherited anemia, such as sickle cell anemia or thalassemias
What Are the Signs and Symptoms of Anemia?
The most common symptom of anemia is fatigue (feeling tired or weak). If you have anemia, it may seem hard to find the energy to do normal activities.
Other signs and symptoms of anemia include:
- Shortness of breath
- Coldness in the hands and feet
- Pale skin
- Chest pain
These signs and symptoms can occur because your heart has to work harder to pump more oxygen-rich blood through your body.
Mild to moderate anemia may cause very mild symptoms or none at all.
Complications of Anemia
Some people who have anemia may have arrhythmias (ah-RITH-me-ahs). An arrhythmia is a problem with the rate or rhythm of the heartbeat. Over time, arrhythmias can damage your heart and possibly lead to heart failure. Anemia also can damage other organs in your body because your blood can’t get enough oxygen to them.
Anemia can weaken people who have cancer or HIV/AIDS. This can make their treatments not work as well.
Anemia also can cause many other medical problems. People who have kidney disease and anemia are more likely to have heart problems. In some types of anemia, too little fluid intake or too much loss of fluid in the blood and body can occur. Severe loss of fluid can be life threatening.
How Is Anemia Diagnosed?
Your doctor will diagnose anemia based on your medical and family histories, a physical exam, and results from tests and procedures.
Because anemia doesn’t always cause symptoms, your doctor may find out you have it while checking for another condition.
Medical and Family Histories
Your doctor may ask whether you have any of the common signs or symptoms of anemia. He or she may ask whether you’ve had an illness or condition that could cause anemia.
Your doctor also may ask about the medicines you take, your diet, and whether you have family members who have anemia or a history of it.
Your doctor will do a physical exam to find out how severe your anemia is and to check for possible causes. He or she may:
- Listen to your heart for a rapid or irregular heartbeat
- Listen to your lungs for rapid or uneven breathing
- Feel your abdomen to check the size of your liver and spleen
Your doctor also may do a pelvic or rectal exam to check for common sources of blood loss.
Diagnostic Tests and Procedures
Your doctor may order various tests or procedures to find out what type of anemia you have and how severe it is.
Complete Blood Count
Often, the first test used to diagnose anemia is a complete blood count (CBC). The CBC measures many different parts of your blood.
This test checks your hemoglobin and hematocrit (hee-MAT-oh-crit) levels. Hemoglobin is the iron-rich protein in red blood cells that carries oxygen to the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A low level of hemoglobin or hematocrit is a sign of anemia.
The normal range of these levels may be lower in certain racial and ethnic populations. Your doctor can explain your test results to you.
The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results may be a sign of anemia, a blood disorder, an infection, or another condition.
Finally, the CBC looks at mean corpuscular (kor-PUS-kyu-lar) volume (MCV). MCV is a measure of the average size of your red blood cells and a clue as to the cause of your anemia. In iron-deficiency anemia, for example, red blood cells usually are smaller than normal.
Other Tests and Procedures
If the CBC results show that you have anemia, you may need other tests such as:
- Hemoglobin electrophoresis (e-lek-tro-FOR-e-sis). This test looks at the different types of hemoglobin in your blood. It can help diagnose the type of anemia you have.
- A reticulocyte (re-TIK-u-lo-site) count. This test measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate.
- Tests for the level of iron in your blood and body. These include serum iron and serum ferritin tests. Transferrin level and total iron-binding capacity also test iron levels.
Because anemia has many causes, you also may be tested for conditions such as kidney failure, lead poisoning (in children), and vitamin deficiencies (lack of vitamins, such as B12 and folic acid).
If your doctor thinks that you have anemia due to internal bleeding, he or she may suggest several tests to look for the source of the bleeding. A test to check the stool for blood may be done in your doctor’s office or at home. Your doctor can give you a kit to help you get a sample at home. He or she will tell you to bring the sample back to the office or send it to a lab.
If blood is found in the stool, other tests may be used to find the source of the bleeding. One such test is endoscopy (en-DOS-ko-pe). For this test, a tube with a tiny camera is used to view the lining of the digestive tract.
Your doctor also may want to do bone marrow tests. These tests show whether your bone marrow is healthy and making enough blood cells.
How Is Anemia Treated?
Treatment for anemia depends on the type, cause, and severity of the condition. Treatments may include dietary changes or supplements, medicines, or procedures.
Goals of Treatment
The goal of treatment is to increase the amount of oxygen that your blood can carry. This is done by raising the red blood cell count and/or hemoglobin level. Another goal is to treat the underlying condition or cause of the anemia.
Dietary Changes and Supplements
Low levels of vitamins or iron in the body can cause some types of anemia. These low levels may be due to poor diet or certain diseases or conditions.
To raise your vitamin or iron levels, your doctor may ask you to change your diet or take vitamin or iron supplements. Common vitamin supplements are vitamin B12 and folic acid (folate). Vitamin C is sometimes given to help the body absorb iron.
Your body needs iron to make hemoglobin. Your body can more easily absorb iron from meats than from vegetables or other foods. To treat your anemia, your doctor may suggest eating more meat—especially red meat, such as beef or liver—as well as chicken, turkey, pork, fish, and shellfish.
Nonmeat foods that are good sources of iron include:
- Spinach and other dark green leafy vegetables
- Peanuts, peanut butter, and almonds
- Peas; lentils; and white, red, and baked beans
- Dried fruits, such as raisins, apricots, and peaches
- Prune juice
Iron is added to some foods, such as cereal, bread, and pasta. You can look at the Nutrition Facts label on a food to find out how much iron it contains. The amount is given as a percentage of the total amount of iron you need every day.
Iron can be given as a mineral supplement. It’s usually combined with multivitamins and other minerals that help your body absorb iron.
Low levels of vitamin B12 can lead to pernicious anemia. This type of anemia is often treated with vitamin B12 supplements.
Good food sources of vitamin B12 include:
- Breakfast cereals with added vitamin B12
- Meats such as beef, liver, poultry, fish, and shellfish
- Egg and dairy products (such as milk, yogurt, and cheese)
Folic acid (folate) is a form of vitamin B that’s found in foods. Your body needs folic acid to make and maintain new cells. Folic acid also is very important for pregnant women. It helps them avoid anemia and promotes healthy growth of the fetus.
Good sources of folic acid include:
- Bread, pasta, and rice with added folic acid
- Spinach and other dark green leafy vegetables
- Black-eyed peas and dried beans
- Beef liver
- Bananas, oranges, orange juice, and some other fruits and juices
Vitamin C helps the body absorb iron. Good sources of vitamin C are vegetables and fruits, especially citrus fruits. Citrus fruits include oranges, grapefruits, tangerines, and similar fruits. Fresh and frozen fruits, vegetables, and juices usually have more vitamin C than canned ones.
If you’re taking medicines, ask your doctor or pharmacist whether you can eat grapefruit or drink grapefruit juice. This fruit can affect the strength of a few medicines and how well they work.
Other fruits rich in vitamin C include kiwi fruit, mangos, apricots, strawberries, cantaloupes, and watermelons.
Vegetables rich in vitamin C include broccoli, peppers, tomatoes, cabbage, potatoes, and leafy green vegetables like romaine lettuce, turnip greens, and spinach.
Your doctor may prescribe medicines to increase the number of red blood cells your body makes or to treat an underlying cause of anemia. Some of these medicines include:
- Antibiotics to treat infections.
- Hormones to treat adult and teenaged women who have heavy menstrual bleeding.
- A man-made version of erythropoietin to stimulate your body to make more red blood cells. This hormone has some risks. You and your doctor will decide whether the benefits of this treatment outweigh the risks.
- Medicines to prevent the body’s immune system from destroying its own red blood cells.
- Chelation (ke-LAY-shun) therapy for lead poisoning. Chelation therapy is used mainly in children. This is because children who have iron-deficiency anemia are at increased risk for lead poisoning.
If your anemia is severe, you may need a medical procedure to treat it. Procedures include blood transfusions and blood and marrow stem cells transplants.
A blood transfusion is a safe, common procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels. Transfusions require careful matching of donated blood with the recipient’s blood.
For more information, see the Diseases and Conditions Index Blood Transfusion article.
Blood and Marrow Stem Cell Transplant
A blood and marrow stem cell transplant replaces your abnormal or faulty stem cells with healthy ones from another person (a donor). Stem cells are found in the bone marrow. They develop into red and white blood cells and platelets.
During the transplant, which is like a blood transfusion, you get donated stem cells through a tube placed in a vein in your chest. Once the stem cells are in your body, they travel to your bone marrow and begin making new blood cells.
For more information, see the Diseases and Conditions Index Blood and Marrow Stem Cell Transplant article.
If you have serious or life-threatening bleeding that’s causing anemia, you may need surgery. For example, you may need surgery to control ongoing bleeding due to a stomach ulcer or colon cancer.
If your body is destroying red blood cells at a high rate, you may need to have your spleen removed. The spleen is an organ that removes worn-out red blood cells from the body. An enlarged or diseased spleen may remove more red blood cells than normal, causing anemia.
How Can Anemia Be Prevented?
You may be able to prevent repeat episodes of some types of anemia, especially those caused by lack of iron or vitamins. Dietary changes or supplements can prevent these types of anemia from occurring again.
Treating the condition’s underlying cause may prevent anemia (or prevent repeat episodes). For example, if your doctor finds out that a medicine is causing your anemia, talk to him or her about other medicine options.
To prevent your anemia from becoming more severe, tell your doctor about all of your signs and symptoms. Discuss the tests you may need with your doctor and follow your treatment plan.
You can’t prevent some types of inherited anemia, such as sickle cell anemia. If you have an inherited anemia, talk to your doctor about treatment and ongoing care.
Living With Anemia
Often, you can treat and control anemia. If you have signs and symptoms of this condition, seek prompt diagnosis and treatment. Treatment may give you a greater energy and activity level, improve your quality of life, and help you live longer.
With proper treatment, many types of anemia are mild and short term. However, anemia can be severe, long lasting, or even fatal when it’s due to an inherited disease, chronic disease, or trauma.
Anemia and Children/Teens
Infants and young children have a greater need for iron because of their rapid growth. Not enough iron can lead to anemia. Preterm and low-birth-weight babies are often watched closely for anemia.
Most of the iron your child needs comes from food. Talk to your child’s doctor about a healthy diet and good sources of iron, vitamins B12 and C, and folic acid (folate). Only give your child iron supplements if the doctor prescribes them. You should carefully follow instructions on how to give your child these supplements.
If your child has anemia, his or her doctor may ask whether the child has been exposed to lead. Lead poisoning in children has been linked to iron-deficiency anemia.
Teenagers are at risk for anemia, especially iron-deficiency anemia, because of their growth spurts. Routine screenings for anemia are often started in the teen years.
Older children and teens who have certain types of severe anemia may be at higher risk for injuries or infections. Talk to your child’s doctor about whether your child needs to avoid high-risk activities, such as contact sports.