What is Anemia?

Anemia is a condition in which the blood does not supply the body with enough oxygen.  This is because, in anemia, either the number of red blood cells circulating in the body is lower than normal  or the levels of hemoglobin inside the red blood cells fall below normal. 

If hemoglobin and/or red blood cell levels are low, less oxygen is delivered to the tissues by the blood.

As a result, people with anemia often feel tired, weak, cold, and short of breath.

Red blood cells (known as “RBC’s” or erythrocytes)  carry oxygen from the lungs to the tissues and remove carbon dioxide and other waste products from the tissues. 

Hemoglobin is the iron-containing red pigment that gives the red blood cells their color; and it also gives red blood cells their ability to carry oxygen.

Anemia is the most common disorder of the red blood cells, affecting about 3.5 million Americans.


hemoglobin, red blood cells and oxygen



Why Does Anemia Occur (What causes anemia)?

There are different causes for anemia.

Anemia occurs if either:

  • The body is not making enough red blood cells (decreased red cell production)
  • The body is destroying too many red blood cells (increased red cell destruction) 
  • The body is losing blood (for example from heavy menstrual periods or internal or external bleeding)
  • The body is lacking the ingredients to produce enough (or healthy) hemoglobin

These different causes of anemia result in many many different types of anemia (different medical conditions).

Thus, anemia is not a disease. Like a fever, anemia indicates that another problem is occurring in the body.

The types of anemia caused by decreases in red cell production include iron deficiency anemia and vitamin deficient anemia.

The type of anemia caused by the body destroying to many red blood cells (and the the bone marrow can’t catch up production of new red blood cells)  is often inherited. The resulting anemia is called hemolytic anemia.

A severe bleeding episode can result in temporary anemia until the body has had time to make up the blood that was lost. But even small, persistent losses of blood may cause anemia if you eat a poor diet. A healthy person whose diet contains plenty of iron and vitamins can produce large amounts of new blood, reducing the risk of anemia.

Iron deficiency is the most common cause of anemia.

A poor diet can cause anemia.

Anemia may result from various health conditions, medications, or treatments such as chemotherapy.

The more severe types of anemia are often inherited.

Women of childbearing age are twice as likely as their male counterparts to have anemia, mostly because women lose iron through menstruation each month. Iron deficiency anemia affects about nine percent of women in the United States,  according to data from the National Center for Health Statistics. Anemia is far more common in resource-poor countries. The World Health Organization (WHO) estimates that two billion people – 30 percent of the world’s population – are anemic. Iron deficiency anemia affects half of women and 40 percent of children in developing countries. Poor diet and infectious diseases are the major causes of anemia in resource-poor countries.


Facts About Anemia

  • The word anemia is Greek for “without blood.”
  • Anemia is a common problem for menstruating women because their iron supplies are depleted monthly.
  • In young children, marrow in all the bones produces red blood cells. As a person ages, red blood cells are eventually produced only in the marrow of the spine, ribs, and pelvis.
  • The life span of a red blood cell is between 90 and 120 days.
  • Old red blood cells are removed from the blood by the liver and spleen, and the iron is returned to the bone marrow to make new cells.
  • The word erythrocyte is derived from the Greek words “erythros” (meaning “red”) and “cyte,” meaning “cell.” Erythrocytes, or red blood cells, were first observed with a microscope in the late 1600s.

Risk Factors for Anemia

Most people can easily avoid anemia by eating an adequate diet that includes enough iron-rich foods. But some people are at greater risk of anemia because of circumstances, illness, family history, genetics, or other factors. Because anemia has many causes, many such risk factors for anemia exist. A few of the most common risk factors are described below.

  • Inadequate iron intake. Not eating enough iron-rich foods is the most common cause of anemia. While most of the developed world has more-than-adequate access to iron-rich foods, resource-poor countries
  • Inadequate intake of vitamin B12. Vitamin B12 plays an important role in the production of red blood cells. Vitamin B12 generally is found  only in animal foods including meat, poultry, fish, eggs, and dairy product (tempeh being the one vegetarian exception to this rule). Strict vegetarians, .
  • Inadequate intake of folate (Vitamin B6). The body needs Vitamin B6 to make hemoglobin. In addition, Vitamin B6 helps increase the oxygen-carrying ability of the blood. Vitamin B6 is found in many foods. Chickpeas (garbanzo beans), beef liver, yellowfin tuna, and salmon are exceptionally rich sources of this vitamin. Most breakfast cereals are fortified with the vitamin: One serving of fortified cereal provides 25 percent of the recommended daily allowance.
  • Intestinal problems. People with underlying intestinal disease such as Crohn’s Disease or celiac disease are at greater risk of developing anemia.
  • Chronic conditions. Many chronic health problems may increase the risk of anemia. These include diabetes, kidney problems, heart disease, thyroid disease, liver disease, and many cancers.  Long-term infections can also contribute to anemia.
  • Pregnancy. A pregnant woman needs to take in enough iron for both her developing fetus and herself. Many pregnant women have difficulty consuming enough iron-rich foods because of pregnancy-related nausea, which is one reason physicians recommend all pregnant women take a multivitamin that contains at least
  • Menstruation. Women who menstruate heavily can lose a significant amount of iron during each period. If this iron loss is not offset by diet or supplements, anemia can result.
  • Family history of anemia. Many types of anemia are inherited. Sickle cell anemia is the most well known of the inherited types of anemia; thalassemia is another inherited disorder that can cause inadequate .
  • Medications. Some medications, especially chemotherapy drugs, can cause anemia. Even common over-the-counter medications can contribute to anemia. For instance, nonsteroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen or naproxyn may cause gastrointestinal bleeding, which in turn can cause anemia. Overuse of heartburn medications can inhibit absorption of Vitamin B12 and contribute indirectly to anemia.

Understanding a bit more about blood:

To understand why anemia occurs, one must first understand a little about the composition and function of blood. Blood is a mixture of plasma (the fluid part of the blood) and cells. Blood is about 55 percent plasma and 45 percent cells.

The blood contains several types of cells, including erythrocytes (red blood cells), white blood cells (which help fight off infection), and platelets (which play a vital role in helping blood to clot). About 99 percent of all cells in the blood are erythrocytes. A healthy adult has about 5 million red blood cells in every cubic millimeter of blood.

Red blood cells are concave in shape, which gives them a greater surface area than other cells. In turn, the greater surface area increases their ability to carry oxygen from the lungs to cells in the body – and carbon dioxide away from cells to the lungs.

red blood cells


Red blood cells are made through an extraordinarily complex process that takes several days to complete. Every second, the body makes about two million red blood cells. The average life of a red blood cell is 120 days.

The actual process of red blood cell production takes place in the red bone marrow, the spongy tissue inside the bones. Production of red blood cells is stimulated by erythropoietin, a hormone made by the kidneys when low levels of oxygen are present in the blood. Erythropoietin stimulates “master cells,” called stem cells, in the bone marrow to differentiate into red blood cells. Once the stem cell “commits” to becoming a red blood cell, it extrudes its nucleus and fills with hemoglobin.

The process of creating and recycling red blood cells is exceptionally complex. Trouble can occur at any point in this process.


National Center for Health Statistics, FastStats. (2011). Anemia or Iron Deficiency. Retrieved from

National Institutes of Health. Office of Dietary Supplements. (2011). Dietary Supplement Fact Sheet: Vitamin B6. Retrieved from

National Institutes of Health. Office of Dietary Supplements. (2011). Dietary Supplement Fact Sheet: Vitamin B12. Retrieved from

World Health Organization. Nutrition, Micronutrient Deficiencies, Iron-deficiency Anemia. Retrieved from:


What Causes Anemia?

There are three general causes of anemia:

  • Decreased red cell production by the bone marrow
  • Increased red cell destruction, or hemolysis
  • Blood loss from heavy menstrual periods or internal bleeding

When you’re anemic, your body either produces too few healthy red blood cells, or destroys them faster than they can be replaced or loses too many of them. If your diet lacks certain vitamins and minerals, the production of hemoglobin can slow down.

Types of anemia caused by decreases in red cell production include iron deficiency anemia and vitamin deficient anemia.

If something in the body destroys or attacks red blood cells, the bone marrow tries to produce more blood. If the destruction of red blood cells is rapid, the marrow can’t catch up. This problem is often inherited. The resulting anemia is called hemolytic anemia.

A severe bleeding episode can result in temporary anemia until the body has had time to make up the blood that was lost. But even small, persistent losses of blood may cause anemia if you have a poor diet. A healthy person whose diet contains plenty of iron and vitamins can produce large amounts of new blood, reducing the risk of anemia.

What Are The Symptoms Of Anemia?

A person with anemia will feel tired and weak. That’s because the body’s tissues are not getting enough oxygen. In fact, fatigue is the main symptom. The severity of symptoms is in part related to how severe the anemia is. Mild cases can occur without symptoms and may be detected only during a medical exam that includes a blood test.

Symptoms of anemia include:

  • Fatigue
  • Weakness
  • Fainting
  • Breathlessness
  • Heart palpitations (rapid or irregular beating)
  • Dizziness
  • Headache
  • Ringing in the ears (tinnitus)
  • Difficulty sleeping
  • Difficulty concentrating

Common signs include:

  • Pale complexion
  • The normally red lining of the mouth and eyelids fades in color
  • Rapid heartbeat (tachycardia)
  • Abnormal menstruation (either absence of periods or increased bleeding)

Other signs depend on the cause. These can include spoon-shaped finger nails and toenails in iron-deficiency anemia, mild jaundice in hemolytic anemias, and leg ulcers in sickle cell anemia .


The Different Kinds Of Anemia

There are different kinds of anemia. Some forms of this condition are inherited, while others are brought on by poor nutrition.

Iron Deficiency Anemia

The body needs iron to produce the hemoglobin necessary for red blood cell production. In general, most people need just 1 milligram of iron daily. Menstruating women need double that dose.

Vitamin Deficiency Anemias

Vitamin B-12 is also essential in hemoglobin production. Normally, a chemical secreted by the stomach helps the body absorbs this vitamin. However, some people can’t readily absorb B-12. The result is B-12 deficiency (pernicious anemia). Because the symptoms develop gradually this condition may not be immediately recognized. Those with thyroid disease or diabetes mellitus are at increased risk for this type of anemia. The condition occurs most often in 40- to 80-year-old northern Europeans with fair skin.

A lack of folic acid, another one of the B vitamins, can also lead to anemia. Folic acid deficiency is a particular problem for alcoholics.

Hemolytic Anemias

Anemia caused by the premature destruction of red blood cells is known as hemolytic anemia. In this type of anemia, antibodies produced by the immune system damage red blood cells. This condition is sometimes associated with disorders such as systemic lupus, or lymphoma.

Toxic materials such as lead, copper, and benzene can also cause the destruction of red blood cells.

Blood transfusions may be necessary for some people with this kind of anemia. Hemolytic anemia can be acquired or inherited. Sickle cell disease and thalassemia are both inherited types of hemolytic anemia.

Sickle Cell Anemia

Sickle cell anemia is also known as Hemoglobin S disease. This is a serious, life-threatening inherited form of anemia. Persons with this disease have sickle-shaped red blood cells that are stiff and unable to squeeze through blood vessels.

Persons with this disease often suffer from pain in the joints and bones. Infections and heart failure can also occur.

The disease occurs in just 0.6 percent of the population, usually in African Americans.


This is a group of anemias due to the defects in the genes producing hemoglobin. It is most common in people of Mediterranean descent. There are two major forms: thalassemia minor and thalassemia major.

As its name implies, thalassemia minor is mild and those suffering from this condition go on to live a full life. Treatment is often unnecessary. Thalassemia major can be serious, but it is very rare. Transfusions or bone marrow transplants are usually required. Thalassemia major is also called Cooley’s anemia, named after the doctor who first described it in 1925.

Aplastic Anemia

This is one of the deadliest and most rare forms of anemia. Only two to six people per million have this type of anemia. The condition results from an unexplained failure of the bone marrow to produce all types of blood cells. Instead, fat cells replace bone marrow.

Aplastic anemia is usually found in adolescents and young adults. Symptoms can include bleeding in the mucous membranes. Chemicals such as benzene and certain pesticides can also cause this type of anemia.

How Is Anemia Diagnosed?

Anemia can be detected by a simple blood test. Most causes can be diagnosed by analysis of blood samples and by examination of the blood cells under a microscope.

A complete blood count test is always performed. The red blood cells and their iron-bearing protein, hemoglobin, are measured. The percentage of red blood cells in the blood is called a hematocrit.

A blood smear will determine the size, shape, and color of the blood cells. The shape of the red blood cells can be distorted in many blood disorders, such as sickle cell anemia.

Iron deficiency anemia is suspected when the red cells are low in number and unusually small. Measuring the amount of iron and its associated proteins in the blood can confirm this diagnosis.

Those with vitamin deficiency anemias have larger-than-normal red blood cells.

In some cases, a bone marrow biopsy may be necessary to confirm a diagnosis. A sample of bone marrow is removed from the back of the pelvic bone or from the breastbone. This sample allows physicians to determine the overall activity of the marrow and whether abnormal cells, such as cancer cells, are interfering with its function.

Other tests that may be needed include chemical examination of the stool for traces of blood, x-rays of the bowel to detect the presence of internal bleeding and examination of the small bowel lining to access its ability to absorb food normally.

How Is Anemia Treated?

The treatment for anemia depends on the type and cause.

  • Iron deficiency anemia is treated with iron (ferrous sulphate) supplements, initially taken three times a day. If nausea, stomach cramps, diarrhea or constipation occur, the medication may be taken with a little bit of food. Treatment should be continued for three to six months in order for the body to fully replenish its iron supply. As long as excessive bleeding is not present and there are no other complicating factors, the anemia will be corrected within a few weeks. However, if the iron deficiency is caused by blood loss that is not due to menstruation, the source of bleeding must be found and stopped. This may require surgery.
  • Pernicious anemia, or vitamin B-12 deficiency, is treated by a life-long course of intramuscular injections of B-12. Persons with this type of anemia receive a shot of B-12 several times a week when first diagnosed. The treatment may continue for life, with one shot about four times a year.
  • Folic acid deficiency anemia can be corrected by taking folic acid supplements once a day.
  • Hereditary hemolytic anemias, such as thalassemia is treated by first eliminating any existing infections and avoiding medications that suppress the body’s immune system. These medications may attack red blood cells. In addition, persons with these types of anemia may require regular blood transfusions.
  • Sickle cell anemia patients may be given oxygen, oral and intravenous fluids and pain-killing drugs to reduce pain and prevent complications. Antibiotics are commonly prescribed as well. Sufferers will need blood transfusions when the anemia becomes severe or if misshapen hemoglobin needs to be replaced. In some cases, a bone marrow transplant may be effective. Adult patients may be treated with the cancer drug hydroxyurea (brand names Droxia, Hydrea).
  • Sometimes rare aplastic anemias and autoimmune hemolytic anemias will respond to steroids. Failure to respond to steroids may require removal of the spleen which can become enlarged with defective red blood cells. Aplastic anemias may require blood transfusions and medications to fight infections.

Other treatment options may be appropriate based on the cause of the anemia.

For instance, if the bone marrow has failed because of leukemia, intensive chemotherapy may be required. Bone marrow transplantation may be contemplated if a suitable donor exists.

With proper treatment, many types of anemia can be eliminated, especially those caused by iron deficiency and vitamin deficiency.

Need To Know:

Most cases of anemia are mild. Without treatment, however, serious problems can occur, since the reduction in red blood cells decreases the ability to absorb oxygen from the lungs.

Certain inherited forms of anemia, including thalassemia major, pernicious anemia, and sickle cell anemia can be life threatening.

You should never self-diagnose yourself with anemia. The symptoms of fatigue and weakness can be the result of many other diseases. If you suspect you have anemia, contact your doctor.

Frequently Asked Questions: Anemia

Here are some frequently asked questions related to anemia.

Q: What is the most common form of anemia?

A: By far, the most common form of anemia worldwide is iron deficiency anemia.

Q: How many different kinds of anemia are there?

A: There are close to 100 different varieties of anemia.

Q: How does drinking an excessive amount of alcohol lead to anemia?

A: Alcohol has a direct toxic effect on the bone marrow which leads to decreased red cell production. People with alcoholism are at risk for anemia both from internal bleeding and vitamin B deficiencies.

Q: I work with chemicals such as benzene. Am I at risk of getting aplastic anemia?

A: Aplastic anemia is exceptionally rare. However, if benzene is spilled and inhaled it can cause this life-threatening condition. It’s important to follow all safety precautions when in contact with this chemical.

Q: I’m expecting twins. Am I at greater risk for becoming anemic?

A: Pregnancy increases the risk for anemia because of the body’s greater demand for folic acid and iron. The risk for women with multiple births is about 27%.

Q: I believe my child may be anemic. How important is it to seek help?

A: You should never self-diagnose anyone with anemia. The symptoms can be indicative of a number of serious diseases. In children, severe anemia can impair growth and motor and mental development, possibly irreversibly.

Putting It All Together: Anemia

Here is a summary of the important facts and information related to anemia.

  • Anemia affects about 3.5 million Americans, making it the most common blood disorder in the U.S.
  • Anemia is the result of below-normal levels of hemoglobin in the red blood cells.
  • There are many different kinds of anemia ranging from mild and easily treatable iron and vitamin deficiency anemias to serious, and sometimes life-threatening aplastic and sickle cell anemias.
  • Fatigue is the main symptom of most anemias.
  • Anemia can be usually be detected with a simple blood test.
  • Treatment of anemia is based on the cause of the disorder. Treatments range from folic acid or vitamin supplements in mild cases to bone marrow transplants in severe cases.
  • You should never self-diagnose anemia. Symptoms of fatigue and weakness can be the result of many other diseases. If you suspect you have anemia, consult your doctor.

Glossary: Anemia

Here are definitions of medical terms related to anemia.

Erythrocyte: A mature red blood cell (RBC)

Hematocrit: The volume of red blood cells in a given volume of blood.

Hemoglobin: Iron-containing pigment of the red blood cells that carries oxygen from the lungs to the tissues.

Hemolysis: The destruction of the membrane of red blood cells.

Jaundice: A condition characterized by yellowness of the skin and whites of the eyes. It may be caused by obstruction of bile passageways, excessive destruction of red blood cells or a disturbance in the liver.

Marrow: The soft tissue occupying the cavities of many bones, including the breastbone. Marrow is of two types: red and yellow. Red marrow is found in spongy bones, yellow is found in the cavities of the long bones.

Plasma: The liquid part of the blood

Spleen: A dark red, oval organ in the upper left abdominal quadrant posterior. The spleen removes old red blood cells from circulation.

Tachycardia: An abnormally rapid heart rate, usually defined as a rate greater than 100 beats per minute.

Additional Sources Of Information: Anemia

Here are some reliable sources that can provide more information on anemia.

Aplastic Anemia & MDS International Foundation 
Phone: 800.747.2820


Sickle Cell Research Foundation 
Phone: 318-487-8019


Cooley’s Anemia Foundation, Inc. (Thalassemia) 
Phone: 800 – 522 – 7222


Cord Blood Banking Information

Provides information on public and private umbilical cord blood collection and storage.


Understanding Anemia, Ed Uthman, May 1998, University Press of Mississippi, ISBN: 1578060397

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