Anemia

If someone has anemia, people may say they have tired blood. That's because anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen to the tissues — can make a person feel tired.

Many types of anemia exist, each with its own cause. Anemia can be caused by an iron or vitamin deficiency, blood loss, a chronic illness, or a genetic or acquired defect or disease. It may also be a side effect of a medication. Anemia can be temporary or chronic. It can range from mild to severe.Anemia affects over three billion people worldwide, including about 3.5 million in the United States. It is the most common blood disorder in the world. Women and people with chronic diseases are at increased risk of the condition.

Although anemia is common, it sometimes can be a complex problem to diagnose and treat because of its many causes. Anemia can signal certain illnesses. Left untreated, it can lead to complications, such as a heart rhythm irregularity. Treatments for anemia range from taking vitamin and iron supplements to undergoing serious medical procedures.

The main symptom of most anemias is fatigue. Other signs and symptoms of anemia in general include:

          • Weakness
          • Pale skin, including decreased pinkness of the lips, gums, lining of the eyelids, nail beds and palms
          • Rapid heartbeat with mild exertion
          • Shortness of breath with mild exertion
          • Chest pain
          • Dizziness, lightheadedness
          • Irritability (in children with anemia)
          • Numbness or coldness in hands and feet

Blood performs a number of crucial functions, including transporting oxygen throughout the body. Blood consists of a liquid called plasma. Floating within this plasma are three types of blood cells — red blood cells, white blood cells and platelets. White blood cells fight infection. Platelets help blood to clot after a cut. Red blood cells (erythrocytes), which are the most abundant of the three types, give blood its red color. They also carry oxygen from the lungs, via the bloodstream, to the brain and the other organs and tissues of the body. A body needs a supply of oxygenated blood to function. Oxygenated blood helps give the body its energy and the skin a healthy glow.

Red blood cells contain hemoglobin — a red, iron-rich protein. Hemoglobin enables red blood cells to carry oxygen from the lungs to all parts of the body.

Most blood cells, including red blood cells, are produced regularly in the bone marrow — a red, spongy material found within the cavities of many of the large bones. To produce hemoglobin and red blood cells, the body needs iron and vitamins from the foods a person eat.

Anemia is a state in which the number of red blood cells or the hemoglobin in them is below normal. When a person're anemic, the 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, the blood is low on red blood cells to carry oxygen to the tissues — leaving a person fatigued. Common types of anemia and their causes include:

Iron deficiency anemia. Anemia can be caused by a shortage of the mineral iron in the body. The bone marrow needs iron to make hemoglobin. Without adequate iron, the body cannot produce enough hemoglobin for red blood cells. The result is iron deficiency anemia. Iron is recycled from old red blood cells, so the blood contains iron. Lose blood, and a person loses 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. The body also gets iron from the foods a person eats. An iron-poor diet or an inability to absorb iron from the foods a person eats because of an intestinal disorder or surgery to the intestines 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, the body needs folic acid 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. They develop vitamin B-12 deficiency anemia (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 (megaloblasts). Vitamin deficiency anemias can be related to the use of certain medications.

Anemia of chronic disease. Certain chronic diseases, such as AIDS, cancer, liver disease and 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 the 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. In some people with rheumatoid arthritis, the bone marrow can't use erythropoietin efficiently, resulting in this type of anemia.

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. A serious infection — such as hepatitis — exposure to toxic chemicals or certain medications can trigger aplastic 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 the body to produce antibodies to red blood cells, destroying them prematurely. Certain medications, such as some 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 serious anemia, which affects mainly blacks, 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. Sickled red blood cells also can block blood flow through small blood vessels in the body, producing other, often painful, symptoms.

Anyone — young or old — whose diet is consistently low in iron and vitamins is at risk of anemia. The body needs iron and vitamins to produce sufficient numbers of red blood cells. Having an intestinal disorder — such as Crohn's disease or celiac disease that affects the absorption of nutrients in the small intestine — puts a person 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.

In general, women are at greater risk of iron deficiency anemia than men. That's because women lose blood — and with it, iron — each month during menstruation. Without iron supplementation, iron deficiency anemia occurs in virtually all pregnant women 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.

If the body have cancer, kidney or liver failure, or another chronic condition, the body 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 the body can deplete the body's store of iron, leading to iron deficiency anemia.

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 an anemia. If the family has a history of an inherited anemia, the body also may be at increased risk of the condition