How Many Types of Anemia Exist?

Anemia is one of the most common blood disorders affecting more than three million people in the United States. However, most people assume that anemia is just that; unknown to them there are different types of anemia. It is important to begin with the understanding that anemia affects red blood cells within the plasma.

Red blood cells carry hemoglobin, an iron-rich protein that attaches to oxygen in the lungs and carries it to tissues throughout the body. Anemia occurs when you do not have enough red blood cells or when your red blood cells do not function properly. It is diagnosed when a blood test shows a hemoglobin value of less than 13.5 gm/dl in a man or less than 12.0 gm/dl in a woman. Normal values for children vary with age.

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Anemia results due to the reduced number or dysfunctional erythrocytes. The role of red blood cells (erythrocytes) is as follows:

Red cells contain a special protein called hemoglobin, which helps carry oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled. Blood appears red because of a large number of red blood cells, which get their color from the hemoglobin. The percentage of whole blood volume that is made up of red blood cells is called the hematocrit and is a common measure of red blood cell levels.

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Erythrocytes are important in the transport of oxygen from the lungs to the rest of the body, and the removal of carbon dioxide from the body to the lungs. The following are the most common types of anemia.

  • Iron-deficiency anemia is the most common type of anemia. It happens when you do not have enough iron in your body. Iron deficiency is usually due to blood loss but may occasionally be due to poor absorption of iron. Pregnancy and childbirth consume a great deal of iron and thus can result in pregnancy-related anemia. People who have had gastric bypass surgery for weight loss or other reasons may also be iron deficient due to poor absorption.
  • Vitamin-deficiency (megaloblastic) anemia may result from low levels of vitamin B12 or folate (folic acid), usually due to inadequate dietary intake. Pernicious anemia is a condition in which vitamin B12 cannot be absorbed in the gastrointestinal tract.
  • Anemia and Pregnancy – Learn about the risk factors and symptoms of anemia during pregnancy.
  • Aplastic anemia is a rare form of anemia that occurs when the body stops making enough red blood cells. Common causes include viral infections, exposure to toxic chemicals, drugs, and autoimmune diseases. Idiopathic aplastic anemia is the term used when the reason for low red blood cell production is not known.
  • Hemolytic anemia occurs when red blood cells are broken up in the bloodstream or in the spleen. Hemolytic anemia may be due to mechanical causes (leaky heart valves or aneurysms), infections, autoimmune disorders, or congenital abnormalities in the red blood cell. Inherited abnormalities may affect the hemoglobin or the red blood cell structure or function. Examples of inherited hemolytic anemia include some types of thalassemia and low levels of enzymes such as glucose-6 phosphate dehydrogenase deficiency. The treatment will depend on the cause.
  • Sickle cell anemia is an inherited hemolytic anemia in which the hemoglobin protein is abnormal, causing the red blood cells to be rigid and clog the circulation because they are unable to flow through small blood vessels.
  • Anemia caused by other diseases – Some diseases can affect the body’s ability to make red blood cells. For example, some patients with kidney disease develop anemia because the kidneys are not making enough of the hormone erythropoietin signal the bone marrow to make new or more red blood cells. Chemotherapy used to treat various cancers often impairs the body’s ability to produce new red blood cells, and anemia often results from this treatment.

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  • Thalassaemia

Thalassemias are inherited blood disorders, which cause the body to make fewer healthy red blood cells and less hemoglobin (an iron-rich protein in red blood cells).
The two major types of thalassemia are alpha- and beta thalassemia. The most severe form of alpha thalassemia is known as alpha thalassemia major or hydrops fetalis while the serious form of beta thalassemia is known as thalassemia major or Cooley’s anemia.
Thalassaemias affect both males and females and occur most often in people of Italian, Greek, Middle Eastern, Asian, and African descent. Severe forms are usually diagnosed in early childhood and are lifelong conditions.

  • Pernicious Anemia

Pernicious anemia is a condition in which the body cannot make enough healthy red blood cells because it does not have enough vitamin B12 (a nutrient found in certain foods). People who have pernicious anemia cannot absorb enough vitamin B12 due to a lack of intrinsic factor (a protein made in the stomach). However, other conditions and factors can also cause vitamin B12 deficiency.

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