Anemia is a condition in which you don't have enough healthy red blood cells to carry adequate oxygen to the body's tissues. Having anemia may make you feel tired and weak.
There are many forms of anemia, each with its own cause. Anemia can be temporary or long term, and it can range from mild to severe. See your doctor if you suspect you have anemia because it can be a warning sign of serious illness.
Treatments for anemia range from taking supplements to undergoing medical procedures. You may be able to prevent some types of anemia by eating a healthy, varied diet.
Anemia signs and symptoms vary depending on the cause of your anemia. They may include:
Pale or yellowish skin
Shortness of breath
Dizziness or lightheadedness
Cold hands and feet
At first anemia can be so mild that it goes unnoticed. But symptoms worsen as anemia worsens.
When to see a doctor
Make an appointment with your doctor if you're feeling fatigued for unexplained reasons. Some anemias, such as iron deficiency anemia or vitamin B-12 deficiency, are common.
Fatigue has many causes besides anemia, so don't assume that if you're tired you must be anemic. Some people learn that their hemoglobin is low, which indicates anemia, when they go to donate blood. If you're told that you can't donate blood because of low hemoglobin, make an appointment with your doctor.
Anemia occurs when your blood doesn't have enough red blood cells. This can happen if:
Your body doesn't make enough red blood cells
Bleeding causes you to lose red blood cells more quickly than they can be replaced
Your body destroys red blood cells
What red blood cells do
Your body makes three types of blood cells — white blood cells to fight infection, platelets to help your blood clot and red blood cells to carry oxygen throughout your body.
Red blood cells contain hemoglobin — an 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 from other parts of the body to your lungs so that it can be exhaled.
Most blood cells, including red blood cells, are produced regularly in your bone marrow — a spongy material found within the cavities of many of your large bones. To produce hemoglobin and red blood cells, your body needs iron, vitamin B-12, folate and other nutrients from the foods you eat.
Causes of anemia
Different types of anemia and their causes include:
Iron deficiency anemia. This is the most common type of anemia worldwide. Iron deficiency anemia is caused by a shortage of 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. Without iron supplementation, this type of anemia occurs in many pregnant women. It is also caused by blood loss, such as from heavy menstrual bleeding, an ulcer, cancer and regular use of some over-the-counter pain relievers, especially aspirin.
Vitamin deficiency anemia. In addition to iron, your body needs folate and vitamin B-12 to produce enough healthy red blood cells. A diet lacking in these and other key nutrients can cause decreased red blood cell production. Additionally, some people may consume enough B-12, but their bodies aren't able to process the vitamin. This can lead to vitamin deficiency anemia, also known as pernicious anemia.
Anemia of chronic disease. Certain diseases — such as cancer, HIV/AIDS, rheumatoid arthritis, kidney disease, Crohn's disease and other chronic inflammatory diseases — can interfere with the production of red blood cells.
Aplastic anemia. This rare, life-threatening anemia occurs when your body doesn't produce enough red blood cells. Causes of aplastic anemia include infections, certain medicines, autoimmune diseases and exposure to toxic chemicals.
Anemias associated with bone marrow disease. A variety of diseases, such as leukemia and myelofibrosis, can cause anemia by affecting blood production in your bone marrow. The effects of these types of cancer and cancer-like disorders vary from mild to life-threatening.
Hemolytic anemias. This group of anemias develops when red blood cells are destroyed faster than bone marrow can replace them. Certain blood diseases increase red blood cell destruction. You can inherit a hemolytic anemia, or you can develop it later in life.
Sickle cell anemia. This inherited and sometimes serious condition is an inherited hemolytic anemia. It's caused by a defective form of hemoglobin that forces red blood cells to assume an abnormal crescent (sickle) shape. These irregular blood cells die prematurely, resulting in a chronic shortage of red blood cells.
Other anemias. There are several other forms of anemia, such as thalassemia and malarial anemia.
These factors place you at increased risk of anemia:
A diet lacking in certain vitamins. Having a diet that is consistently low in iron, vitamin B-12 and folate increases your risk of anemia.
Intestinal disorders. Having an intestinal disorder that affects the absorption of nutrients in your small intestine — such as Crohn's disease and celiac disease — puts you at risk of anemia.
Menstruation. In general, women who haven't experienced menopause have a greater risk of iron deficiency anemia than do men and postmenopausal women. That's because menstruation causes the loss of red blood cells.
Pregnancy. If you're pregnant and aren't taking a multivitamin with folic acid, you're at an increased risk of anemia.
Chronic conditions. If you have cancer, kidney 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 your 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, such as sickle cell anemia, you also may be at increased risk of the condition.
Other factors. A history of certain infections, blood diseases and autoimmune disorders, alcoholism, exposure to toxic chemicals, and the use of some medications can affect red blood cell production and lead to anemia.
Age. People over age 65 are at increased risk of anemia.
Left untreated, anemia can cause many health problems, such as:
Severe fatigue. When anemia is severe enough, you may be so tired that you can't complete everyday tasks.
Pregnancy complications. Pregnant women with folate deficiency anemia may be more likely to experience complications, such as premature birth.
Heart problems. Anemia can lead to a rapid or irregular heartbeat (arrhythmia). When you're anemic your heart must pump more blood to compensate for the lack of oxygen in the blood. This can lead to an enlarged heart or heart failure.
Death. 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.
To diagnose anemia, your doctor may ask you about your medical and family history, perform a physical exam, and run the following tests:
Complete blood count (CBC). A CBC is used to count the number of blood cells in a sample of your blood. For anemia your doctor will be interested in the levels of the red blood cells contained in the blood (hematocrit) and the hemoglobin in your blood. Normal adult hematocrit values vary from one medical practice to another but are generally between 40 and 52 percent for men and 35 and 47 percent for women. Normal adult hemoglobin values are generally 14 to 18 grams per deciliter for men and 12 to 16 grams per deciliter for women.
A test to determine the size and shape of your red blood cells. Some of your red blood cells may also be examined for unusual size, shape and color.
Additional diagnostic tests
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 ulcers, benign polyps in the colon, colon cancer, tumors or kidney problems.
Occasionally, it may be necessary to study a sample of your 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 making changes to your diet. 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. Treatment for folic acid and B-12 deficiency involves dietary supplements and increasing these nutrients in your diet. If your digestive system has trouble absorbing vitamin B-12 from the food you eat, you may need vitamin B-12 shots. At first, you may receive the shots every other day. Eventually, you'll need shots just once a month, which may continue for life, depending on your situation.
Anemia of chronic disease. There's no specific treatment for this type of anemia. Doctors focus on treating the underlying disease. If symptoms become severe, a blood transfusion or injections of synthetic erythropoietin, a hormone normally produced by your kidneys, may help stimulate red blood cell production and ease fatigue.
Aplastic anemia. Treatment for this 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.
Anemias associated with bone marrow disease. Treatment of these various diseases can include medication, chemotherapy or bone marrow transplantation.
Hemolytic anemias. 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. Depending on the severity of your anemia, a blood transfusion or plasmapheresis may be necessary. Plasmapheresis is a type of blood-filtering procedure. In certain cases, removal of the spleen can be helpful.
Sickle cell anemia. Treatment for this anemia may include the administration of oxygen, pain-relieving drugs, and oral and intravenous fluids to reduce pain and prevent complications. Doctors also may recommend 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.
Thalassemia. This anemia may be treated with blood transfusions, folic acid supplements, medication, removal of the spleen (splenectomy), or a blood and bone marrow stem cell transplant.