Anemias - Description

Cells require a constant supply of oxygen in order to stay healthy. Oxygen is delivered to cells by red blood cells, which pick up oxygen in the lungs. They carry the oxygen to cells through the bloodstream.

The oxygen-carrying molecule in red blood cells is hemoglobin (pronounced HEE-muh-glo-bin). Hemoglobin is a large, complex molecule. It contains an atom of iron at its center. Iron attaches itself easily to oxygen atoms. It is the iron in hemoglobin that actually carries oxygen to cells.

Anemia develops when the body has an insufficient supply of red blood cells and hemoglobin. When that happens, cells do not get the oxygen they need and begin to die off. A variety of medical problems may develop.

Types of Anemia

More than four hundred different kinds of anemia have been identified. Many of them are rare. Some are mild medical problems, while others are moderate or serious. Some are so serious that they may cause death. A few of the most common forms of anemia include the following.

IRON DEFICIENCY ANEMIA. Iron deficiency anemia is the most common form of anemia in the world. In the United States the condition primarily affects young children and women. About 240,000 children between the ages of one and two have the condition. About 3.3 million women of child-bearing age have iron deficiency anemia.

The onset (beginning) of iron deficiency anemia is gradual. There may be no symptoms at first. As the name suggests, iron deficiency anemia occurs when the body does not have enough iron to make all the red blood cells it needs. Red blood cells die off faster than they can be made by the body.

FOLIC ACID DEFICIENCY ANEMIA. Folic acid is a member of the vitamin B family. It is used in the production of new red blood cells. Some people do not get enough folic acid in their normal diet, so their bodies are unable to produce enough red blood cells. In other cases, the body may not be able to properly use the folic acid eaten.

Folic acid deficiency anemia occurs most often in infants and teenagers. Some important sources of folic acid are cheese, eggs, fish, green vegetables, meat, milk, and yeast. Smoking can also interfere with the body's ability to use folic acid.

VITAMIN B ₁₂ DEFICIENCY ANEMIA. Like folic acid, vitamin B ₁₂ is used to make red blood cells. The vitamin is found in meat and vegetables. Some symptoms of vitamin B ₁₂ deficiency anemia are loss of muscle control, loss of feeling in the arms and legs, soreness of the tongue, and weight loss.

The most common form of vitamin B ₁₂ deficiency anemia is called pernicious anemia. People between the ages of fifty and sixty are at highest risk for pernicious anemia. Some conditions that can lead to pernicious anemia are eating disorders (see anorexia nervosa and bulimia entries), poor nutrition, diabetes mellitus (pronounced DI-uh-BEE-teez MEH-luh-tuss; see diabetes mellitus entry), stomach problems, and thyroid disease.

HEMOLYTIC ANEMIA. Hemolytic (pronounced HEE-muh-lit-ik) anemia occurs when red blood cells are destroyed faster than they are made. In some cases, an infection can cause this problem. In other cases, the body's own immune system destroys the red blood cells. Some symptoms of hemolytic anemia include pain, shock, gallstones, an enlarged spleen, and other serious health problems.

THALASSEMIAS. Thalassemias (pronounced thal-uh-SEE-mee-uhs) are caused by the body's inability to manufacture enough red blood cells. The condition is a genetic disorder, meaning that parents who have a gene for the condition may pass it to their children. Genes are chemical units in the body that tell cells what functions to perform. In people who have defective thalassemia genes, cells have lost the instructions needed to produce red blood cells.

AUTOIMMUNE HEMOLYTIC ANEMIAS. An autoimmune disorder is one in which a person's immune system attacks its own body. The normal function of the immune system is to protect the body against foreign invaders, such as bacteria and viruses. But the immune system can sometimes become confused. It thinks that parts of the body are a foreign invader. In the case of autoimmune hemolytic anemias, the immune system attacks red blood cells, killing them just as it would destroy bacteria or viruses.

SICKLE CELL ANEMIA. Sickle cell anemia (see sickle cell anemia entry) is a genetic disorder. Cells receive genes that give them the wrong instructions for making red blood cells. Red blood cells are normally shaped like plump doughnuts. In sickle cell anemia, the cells are curved with sharp points. These cells easily stick to each other. They also stick to the walls of blood vessels. Clumps of sickled red blood cells can collect in a vein or artery and block it. This condition can cause pain, weakness, and, in extreme cases, death.

APLASTIC ANEMIA. Aplastic anemia is a serious form of anemia that can lead to death. The body makes too few of all kinds of blood cells: red blood cells, white blood cells, and platelets (pronounced PLATE-lits). Platelets are blood cells that help blood to clot. Aplastic anemia may be caused by a recent severe illness, long-term exposure to industrial chemicals, and the use of certain types of medication.