Anemia is a condition in which you lack enough healthy red blood cells to carry adequate oxygen to your body's tissues. Having anemia, also referred to as low hemoglobin, can 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 can range from mild to severe. In most cases, anemia has more than one cause. See your doctor if you suspect that you have anemia. It can be a warning sign of serious illness.
Treatments for anemia, which depend on the cause, range from taking supplements to having medical procedures. You might be able to prevent some types of anemia by eating a healthy, varied diet.
Iron deficiency anemia
Sickle cell anemia
Vitamin deficiency anemia
Anemia signs and symptoms vary depending on the cause and severity of anemia. Depending on the causes of your anemia, you might have no symptoms.
Signs and symptoms, if they do occur, might include:
Pale or yellowish skin
Shortness of breath
Dizziness or lightheadedness
Cold hands and feet
At first, anemia can be so mild that you don't notice it. But symptoms worsen as anemia worsens.
When to see a doctor
Make an appointment with your doctor if you feel fatigued and you don't know why.
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 donate blood. If you're told that you can't donate because of low hemoglobin, make an appointment with your doctor.
Anemia can be due to a condition present at birth (congenital) or to a condition you develop (acquired). 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 from your lungs to the rest of your body and carbon dioxide from the body back to the lungs.
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 to 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 have different causes. They include:
Iron deficiency anemia. This most common type of 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's also caused by blood loss, such as from heavy menstrual bleeding; an ulcer in the stomach or small bowel; cancer of the large bowel; and regular use of some pain relievers that are available without a prescription, especially aspirin, which can cause inflammation of the stomach lining resulting in blood loss. It's important to determine the source of iron deficiency to prevent recurrence of the anemia.
Vitamin deficiency anemia. Besides 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. Some people who consume enough B-12 aren't able to absorb the vitamin. This can lead to vitamin deficiency anemia, also known as pernicious anemia.
Anemia of inflammation. Certain diseases — such as cancer, HIV/AIDS, rheumatoid arthritis, kidney disease, Crohn's disease and other acute or 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 a 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.
These factors place you at increased risk of anemia:
A diet lacking in certain vitamins and minerals. A diet consistently low in iron, vitamin B-12, folate and copper 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 had menopause have a greater risk of iron deficiency anemia than do men and postmenopausal women. Menstruation causes the loss of red blood cells.
Pregnancy. Being pregnant and not taking a multivitamin with folic acid and iron, increases your risk of anemia.
Chronic conditions. If you have cancer, kidney failure or another chronic condition, you could 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 might be at increased risk of the condition.
Other factors. A history of certain infections, blood diseases and autoimmune disorders increases your risk of anemia. 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:
Extreme fatigue. Severe anemia can make you so tired that you can't complete everyday tasks.
Pregnancy complications. Pregnant women with folate deficiency anemia can be more likely to have complications, such as premature birth.
Heart problems. Anemia can lead to a rapid or irregular heartbeat (arrhythmia). When you're anemic your heart pumps more blood to make up 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 lead to life-threatening complications. Losing a lot of blood quickly results in acute, severe anemia and can be fatal. Among older people, anemia is associated with an increased risk of death.
Many types of anemia can't be prevented. But you can avoid iron deficiency anemia and vitamin deficiency anemias by eating a diet that includes a variety of vitamins and minerals, including:
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 synthetic 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 cereal and soy products.
Vitamin C. Foods rich in vitamin C include citrus fruits and juices, peppers, broccoli, tomatoes, melons and strawberries. These also help increase iron absorption.
If you're concerned about getting enough vitamins and minerals from food, ask your doctor whether a multivitamin might help.
To diagnose anemia, your doctor is likely to 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 likely be interested in the levels of the red blood cells contained in your blood (hematocrit) and the hemoglobin in your blood. Healthy adult hematocrit values are generally between 38.3% and 48.6% for men and 35.5% and 44.9% for women. Healthy adult hemoglobin values are generally 13.2 to 16.6 grams per deciliter for men and 11.6 to 15 grams per deciliter for women. These values may differ slightly from one medical practice to another. Numbers might be lower for people who engage in intense physical activity, are pregnant or of older age. Smoking and being at high altitude might increase numbers.
A test to determine the size and shape of your red blood cells. Some of your red blood cells might also be examined for unusual size, shape and color.
Additional diagnostic tests
If you receive a diagnosis of anemia, your doctor might order other tests to determine the cause. Occasionally, it can 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 changing your diet. For some people, this might involve receiving iron through a vein. If the cause of iron deficiency is loss of blood — other than from menstruation — the source of the bleeding must be located and the bleeding stopped. This might involve surgery.
Vitamin deficiency anemias. Treatment for folic acid and vitamin C 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 might need vitamin B-12 shots. At first, you might have the shots every other day. Eventually, you'll need shots just once a month, possibly 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 a synthetic hormone normally produced by your kidneys (erythropoietin) might help stimulate red blood cell production and ease fatigue.
Aplastic anemia. Treatment for this anemia can include blood transfusions to boost levels of red blood cells. You might need a bone marrow transplant if your bone marrow 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 infections and taking drugs that suppress your immune system, which could be attacking your red blood cells. Severe hemolytic anemia generally needs ongoing treatment.
Sickle cell anemia. Treatment might include oxygen, pain relievers, and oral and intravenous fluids to reduce pain and prevent complications. Doctors might also recommend blood transfusions, folic acid supplements and antibiotics. A cancer drug called hydroxyurea (Droxia, Hydrea, Siklos) also is used to treat sickle cell anemia.
Thalassemia. Most forms of thalassemia are mild and require no treatment. More-severe forms of thalassemia generally require blood transfusions, folic acid supplements, medication, removal of the spleen, or a blood and bone marrow stem cell transplant.
Preparing for your appointment
Make an appointment with your primary care doctor if you have prolonged fatigue or other signs or symptoms that worry you. He or she may refer you to a doctor who specializes in treating blood disorders (hematologist), the heart (cardiologist) or the digestive system (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, implanted medical devices, exposure to toxins or chemicals, and recent life changes
All medications, vitamins and other supplements you take, including the doses
Questions to ask your doctor
For anemia, basic questions to ask your doctor include:
What's the most likely cause of my symptoms?
Are there other possible causes?
Do I need tests?
Is my anemia likely temporary or long lasting?
What treatments are available, 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 restrict my diet?
Do I need to add foods to my diet? How often do I need to eat these foods?
Do you have brochures or other printed materials I can take? What websites do you recommend?
What to expect from your doctor
Your doctor is likely to ask you questions, such as:
Do your symptoms come and go or are they constant?
How severe are your symptoms?
Does anything seem to improve your symptoms?
What, if anything, appears to worsen your symptoms?
Are you a vegetarian?
How many servings of fruits and vegetables do you usually eat in a day?
Do you drink alcohol? If so, how often, and how many drinks do you usually have?
Are you a smoker?
Have you recently donated blood more than once?
By Mayo Clinic Staff