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.  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.  Anemia is a common blood disorder. Women and people with chronic diseases are at increased risk of the condition.  Anemia can be a sign of serious illnesses. 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.
The main symptom of most types of anemia is fatigue. Other anemia symptoms include:

  • Weakness
  • Pale skin
  • A fast or irregular heartbeat
  • Shortness of breath
  • Chest pain
  • Dizziness
  • Cognitive problems
  • Numbness or coldness in your extremities
  • Headache

Initially, anemia can be so mild it goes unnoticed. But signs and symptoms increase as the condition worsens.
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 about one in five women, half of pregnant women and 3 percent of men in the United States. The cause is a shortage of the element 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 needed 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. 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 sometimes called 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.
  • Anemia of chronic disease. Certain chronic diseases — such as cancer, rheumatoid arthritis, Crohn’s disease and other chronic inflammatory diseases — 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. Many times, the cause of aplastic anemia is unknown, but it’s believed to often 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, a pre-leukemic condition, 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, life-threatening shutdown of the blood-making process. Additionally, other cancers of the blood or bone marrow, such as multiple myeloma, myeloproliferative disorders and 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 can also 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.
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 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 vitamin B-12 in their diet. 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, protein 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 and 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 what’s called 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.
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 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, colon cancer, tumors, or kidney failure. 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.
If you’ve been diagnosed with anemia — it’s often detected during routine blood tests — ask your doctor what treatment is necessary. Then be sure to follow through on treatment, even if you quickly 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 congestive heart failure. 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.

Anemia treatment 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 lessen your immune system’s response and give the transplanted 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 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. 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 need 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.
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 and other meats. Other foods rich in iron include beans, lentils, iron-fortified cereals, dark green leafy vegetables, dried fruit, nuts and seeds. Folate, and its synthetic form, folic acid, can be found in citrus juices and fruits, dark green leafy vegetables, legumes and fortified breakfast cereals. Vitamin B-12 is plentiful in meat and dairy products. Foods containing vitamin C, such as citrus fruits, 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.