Anemia is a problem of not having enough healthy red blood cells or hemoglobin to carry oxygen to the body's tissues. Hemoglobin is a protein found in red cells that carries oxygen from the lungs to all other organs in the body. Having anemia can cause tiredness, weakness and shortness of breath.

There are many forms of anemia. Each has its own cause. Anemia can be short term or long term. It can range from mild to severe. Anemia can be a warning sign of serious illness.

Treatments for anemia might involve taking supplements or having medical procedures. Eating a healthy diet might prevent some forms of anemia.

Anemia symptoms depend on the cause and how bad the anemia is. Anemia can be so mild that it causes no symptoms at first. But symptoms usually then occur and get worse as the anemia gets worse.

If another disease causes the anemia, the disease can mask the anemia symptoms. Then a test for another condition might find the anemia. Certain types of anemia have symptoms that point to the cause.

Possible symptoms of anemia include:

• Tiredness.
• Weakness.
• Shortness of breath.
• Pale or yellowish skin, which might be more obvious on white skin than on Black or brown skin.
• Irregular heartbeat.
• Dizziness or lightheadedness.
• Chest pain.
• Cold hands and feet.
• Headaches.

When to see a doctor

Make an appointment with your health care provider if you're tired or short of breath and don't know why.

Low levels of the protein in red blood cells that carry oxygen, called hemoglobin, is the main sign of anemia. Some people learn they have low hemoglobin when they donate blood. If you're told that you can't donate because of low hemoglobin, make a medical appointment.

Anemia occurs when the blood doesn't have enough hemoglobin or red blood cells.

This can happen if:

• The body doesn't make enough hemoglobin or red blood cells.
• Bleeding causes loss of red blood cells and hemoglobin faster than they can be replaced.
• The body destroys red blood cells and the hemoglobin that's in them.

What red blood cells do

The body makes three types of blood cells. White blood cells fight infection, platelets help blood clot and red blood cells carry oxygen throughout the body.

Red blood cells have an iron-rich protein that gives blood its red color, called hemoglobin. Hemoglobin lets red blood cells carry oxygen from the lungs to all parts of the body. And it lets red blood cells carry carbon dioxide from other parts of the body to the lungs to be breathed out.

Spongy matter inside many of the large bones, called bone marrow, makes red blood cells and hemoglobin. To make them, the body needs iron, vitamin B-12, folate and other nutrients from foods.

Causes of anemia

Different types of anemia have different causes. They include:

• Iron deficiency anemia. Too little iron in the body causes this most common type of anemia. Bone marrow needs iron to make hemoglobin. Without enough iron, the body can't make enough hemoglobin for red blood cells.

  Pregnant people can get this type of anemia if they don't take iron supplements. Blood loss also can cause it. Blood loss might be from heavy menstrual bleeding, an ulcer, cancer or regular use of some pain relievers, especially aspirin.

• Vitamin deficiency anemia. Besides iron, the body needs folate and vitamin B-12 to make enough healthy red blood cells. A diet that doesn't have enough of these and other key nutrients can result in the body not making enough red blood cells.

  Also, some people can't absorb vitamin B-12. This can lead to vitamin deficiency anemia, also called pernicious anemia.

• Anemia of inflammation. Diseases that cause ongoing inflammation can keep the body from making enough red blood cells. Examples are cancer, HIV/AIDS, rheumatoid arthritis, kidney disease and Crohn's disease.
• Aplastic anemia. This rare, life-threatening anemia occurs when the body doesn't make enough new blood cells. Causes of aplastic anemia include infections, certain medicines, autoimmune diseases and being in contact with toxic chemicals.
• Anemias linked to bone marrow disease. Diseases such as leukemia and myelofibrosis can affect how the bone marrow makes blood. The effects of these types of diseases range from mild to life-threatening.
• Hemolytic anemias. This group of anemias is from red blood cells being destroyed faster than bone marrow can replace them. Certain blood diseases increase how fast red blood cells are destroyed. Some types of hemolytic anemia can be passed through families, which is called inherited.
• Sickle cell anemia. This inherited and sometimes serious condition is a type of hemolytic anemia. An unusual hemoglobin forces red blood cells into an unusual crescent shape, called a sickle. These irregular blood cells die too soon. That causes an ongoing shortage of red blood cells.

These factors can increase risk of anemia:

• A diet that doesn't have enough of certain vitamins and minerals. Not getting enough iron, vitamin B-12 and folate increases the risk of anemia.
• Problems with the small intestine. Having a condition that affects how the small intestine takes in nutrients increases the risk of anemia. Examples are Crohn's disease and celiac disease.
• Menstrual periods. In general, having heavy periods can create a risk of anemia. Having periods causes the loss of red blood cells.
• Pregnancy. Pregnant people who don't take a multivitamin with folic acid and iron are at an increased risk of anemia.

• Ongoing, called chronic, conditions. Having cancer, kidney failure, diabetes or another chronic condition increases the risk of anemia of chronic disease. These conditions can lead to having too few red blood cells.

  Slow, chronic blood loss from an ulcer or other source within the body can use up the body's store of iron, leading to iron deficiency anemia.

• Family history. Having a family member with a type of anemia passed through families, called inherited, can increase the risk of inherited anemias, such as sickle cell anemia.
• Other factors. A history of certain infections, blood diseases and autoimmune conditions increases the risk of anemia. Drinking too much alcohol, being around toxic chemicals, and taking some medicines can affect the making of red blood cells and lead to anemia.
• Age. People over age 65 are at increased risk of anemia.

If not treated, anemia can cause many health problems, such as:

• Severe tiredness. Severe anemia can make it impossible to do everyday tasks.
• Pregnancy complications. Pregnant people with folate deficiency anemia may be more likely to have complications, such as premature birth.
• Heart problems. Anemia can lead to a rapid or irregular heartbeat, called arrhythmia. With anemia, the heart must pump more blood to make up for too little oxygen in the blood. This can lead to an enlarged heart or heart failure.
• Death. Some inherited anemias, such as sickle cell anemia, can lead to life-threatening complications. Losing a lot of blood quickly causes severe anemia and can be fatal.

Many types of anemia can't be prevented. But eating a healthy diet might prevent iron deficiency anemia and vitamin deficiency anemias. A healthy diet includes:

• Iron. Iron-rich foods include beef and other meats, beans, lentils, iron-fortified cereals, dark green leafy vegetables, and dried fruit.
• Folate. This nutrient, and its human-made form folic acid, can be found in fruits and fruit juices, dark green leafy vegetables, green peas, kidney beans, peanuts, and enriched grain products, such as bread, cereal, pasta and rice.
• Vitamin B-12. Foods rich in vitamin B-12 include meat, dairy products, and fortified cereals and soy products.
• Vitamin C. Foods rich in vitamin C include citrus fruits and juices, peppers, broccoli, tomatoes, melons, and strawberries. These also help the body take in iron.

If you're concerned about getting enough vitamins and minerals from food, ask your health care provider about taking a multivitamin.

To diagnose anemia, your health care provider is likely to ask you about your medical and family history, do a physical exam, and order blood tests. Tests might include:

• Complete blood count (CBC). A CBC is used to count the number of blood cells in a sample of blood. For anemia, the test measures the amount of the red blood cells in the blood, called hematocrit, and the level of hemoglobin in the blood.

  Typical adult hemoglobin values are generally 14 to 18 grams per deciliter for men and 12 to 16 grams per deciliter for women. Typical adult hematocrit values vary among medical practices. But they're generally between 40% and 52% for men and 35% and 47% for women.

• A test to show the size and shape of the red blood cells. This looks at the size, shape and color of the red blood cells.

Other diagnostic tests

If you get a diagnosis of anemia, you might need more tests to find the cause. Sometimes, it can be necessary to study a sample of bone marrow to diagnose anemia.

Anemia treatment depends on the cause.

• Iron deficiency anemia. Treatment for this form of anemia usually involves taking iron supplements and changing the diet.

  If the cause of iron deficiency is loss of blood, finding the source of the bleeding and stopping it is needed. This might involve surgery.

• Vitamin deficiency anemias. Treatment for folic acid and vitamin B-12 deficiency involves dietary supplements and increasing these nutrients in the diet.

  People who have trouble absorbing vitamin B-12 from food might need vitamin B-12 shots. At first, the shots are every other day. In time, the shots will be shots just once a month, possibly for life.

• Anemia of chronic disease. Treatment for this type of anemia focuses on the disease that's causing it. If symptoms become severe, treatment might include getting blood, called a transfusion, or shots of a hormone called erythropoietin.
• Anemias associated with bone marrow disease. Treatment of these various diseases can include medicines, chemotherapy or getting bone marrow from a donor, called a transplant.
• Aplastic anemia. Treatment for this anemia can include blood transfusions to boost levels of red blood cells. A bone marrow transplant might be needed if bone marrow can't make healthy blood cells.
• Hemolytic anemias. Managing hemolytic anemias includes stopping medicines that might be causing it and treating infections. If the immune system is attacking red blood cells, treatment might involve taking medicines that lower immune system activity.

• Sickle cell anemia. Treatment might include oxygen, pain relievers, and hydration with fluids given through a vein, called intravenous, to reduce pain and prevent complications. Receiving blood, called a transfusion, and taking folic acid supplements and antibiotics might be involved.

  A cancer drug called hydroxyurea (Droxia, Hydrea, Siklos) also is used to treat sickle cell anemia.

• Thalassemia. Most forms of thalassemia are mild and need no treatment. More-severe forms of thalassemia generally require blood transfusions, folic acid supplements, medicines, a blood and bone marrow stem cell transplant, or, rarely, removing the spleen.

Make an appointment with your primary care provider if you have long-lasting fatigue or other symptoms that worry you. You might end up seeing a doctor who specializes in treating blood disorders, called a hematologist; the heart, called a cardiologist; or the digestive system, called a gastroenterologist.

Here's some information to help you get ready for your appointment.

What you can do

Before your appointment, make a list of:

• Your symptoms and when they began.
• Key personal information, including major stresses, medical devices you have in your body, toxins or chemicals you've been around, and recent life changes.
• All medicines, vitamins and other supplements you take, including the doses.
• Questions to ask your health care provider.

For anemia, basic questions to ask include:

• What's the most likely cause of my symptoms?
• Are there other possible causes?
• What tests do I need?
• Is my anemia likely short term or long lasting?
• What treatments are there, and which do you recommend?
• What side effects can I expect from treatment?
• I have other health conditions. How can I best manage them together?
• Do I need to change my diet?
• Do you have brochures or other printed materials I can have? What websites do you recommend?

What to expect from your doctor

Your health care provider is likely to ask you questions, such as:

• Do your symptoms come and go or are they constant?
• How bad are your symptoms?
• Does anything seem to make your symptoms better?
• What, if anything, appears to make your symptoms worse?
• Are you a vegetarian?
• How many servings of fruits and vegetables do you eat in a day?
• Do you drink alcohol? If so, how often, and how many drinks do you have?
• Are you a smoker?
• Have you recently donated blood more than once?