Home   >   Medicine   >   Immunological Disorders
Pernicious Anemia

Pernicious anemia is a condition in which the body does not make enough red blood cells due to a lack of vitamin B12 in the body. It usually occurs in people whose bodies have lost the ability to absorb vitamin B12 from food.


Major Signs and Symptoms

Major signs and symptoms of pernicious anemia are feeling tired and weak and having a bright red, smooth tongue. Common symptoms of nerve damage caused by this disease are tingling and numbness in the hands and feet.

Symptoms most often develop slowly over time if the disease is not treated. Some people may experience mental changes and nerve problems before blood tests show that they have anemia. This is more likely to happen in older adults than in younger people.

Other Signs and Symptoms

Other signs and symptoms of pernicious anemia may include pale or yellowish skin, a low-grade fever, and dizziness when standing up. Infants with the condition may show unusual movements or a delayed development and failure to thrive.


Complications seen with pernicious anemia can involve the heart, nerves and brain, and digestive tract. Some of the complications are due to the anemia; others are the effect of a low vitamin B12 level on parts of the body.

Signs and symptoms of heart problems may include shortness of breath and chest pain. Heart murmurs, a rapid heart rate, and heart failure can develop.

Nerves and Brain
In addition to tingling or numbness in the hands and feet, signs and symptoms of problems with the nerves may include difficulty walking, unsteady movement, and loss of balance. There can be changes in vision, taste, and smell. Memory loss, confusion, depression, and even psychosis can develop.

Digestive Tract
Signs and symptoms of untreated pernicious anemia can occur all along the digestive track. They can start with a bright red, smooth tongue and may include mouth sores or bleeding gums. The liver could be enlarged. Nausea and vomiting may occur, along with a sense of fullness, gas, or heartburn. Changes in bowel habits could include constipation or diarrhea. A person might have a loss of appetite or weight loss.


Major Causes

Pernicious anemia is caused by a lack of vitamin B12 in the body. The main reason for the vitamin B12 deficiency is the loss of parietal cells in the lining of the stomach. These cells make intrinsic factor, which helps the body absorb vitamin B12 in the small intestine. In some people, the body's immune system may attack and destroy the parietal cells. Doctors don't know exactly why or how this happens, or if the immune system produces antibodies in reaction to normally aging or dying parietal cells.

As a result of this immune system attack, the stomach lining shrinks, and the parietal cells in the lining of the stomach disappear. The stomach stops producing intrinsic factor. Over time, vitamin B12 deficiency develops.

Loss of intrinsic factor can also be due to removal of the stomach lining in various kinds of stomach surgery. This surgery includes removal of all or part of the stomach as well as stomach surgery for weight loss.

There is also a rare inherited disorder in which children are born without the ability to produce intrinsic factor.

Other Causes

Less common causes of pernicious anemia include a diet low in vitamin B12, intestinal problems, and certain medicines.

Lack of Vitamin B12 in the Diet

People can develop pernicious anemia if they don't get enough vitamin B12 in the foods that they eat. This condition takes many years to develop because it takes time to use up the vitamin B12 already stored in the body.

Some people who are strict vegetarians can develop pernicious anemia, especially if they do not eat meat, poultry, fish, eggs, or dairy products - the best food sources of vitamin B12. Breastfed infants of strict vegetarian mothers can develop anemia in a short time because they don't have enough vitamin B12 stored in their bodies. They can be given vitamin B12 supplements to prevent this type of anemia.

Some people develop pernicious anemia because of a poor diet due to conditions such as alcoholism or aging.

Disorders of the Small Intestine

Some intestinal problems can cause poor absorption of vitamin B12. These problems include:

  • An infection caused by parasites or an overgrowth of bacteria in the intestine
  • Celiac disease (also known as sprue), a genetic disorder that makes a person unable to tolerate gluten
  • Crohn's disease, an inflammatory bowel disease
  • Not enough stomach acid to digest food - a problem that can occur in older adults

Long-term use of certain medicines may lead to pernicious anemia. Examples of these are medicines that reduce acid in the stomach and certain diabetes medicines (such as metformin, phenformin, and biguanides).


Doctors treat pernicious anemia by replacing the missing vitamin B12 in the body. People who have pernicious anemia need treatment, usually for the rest of their lives. Without treatment, pernicious anemia can cause serious problems and can even be fatal.

Goals of Treatment

The goals of treating pernicious anemia are to:

  • Stop the anemia and symptoms through vitamin B12 treatment
  • Prevent complications, such as heart or nerve damage
  • Provide ongoing followup to make sure that the treatment is working
  • Treat the underlying cause, if one can be found
Specific Types of Treatment

Fortunately, pernicious anemia is usually easy to treat with either vitamin shots (injections) or pills. Symptoms may begin to improve within a few days after the start of treatment.

  • Vitamin B12 shots. People with pernicious anemia may get daily or weekly shots at first, then one shot every month. Some people get vitamin B12 shots and also take vitamin B12 pills.
  • Vitamin B12 pills. Many people with pernicious anemia can be treated successfully with vitamin B12 pills. Often, the pills work as well as the shots. Because only a small amount of vitamin B12 is absorbed by the body, high doses are given.

Vitamin B12 can also be given in a gel or spray for the nose.

Treatment for the underlying causes of vitamin B12 deficiency may be needed. To help the body absorb vitamin B12, for example, a person might need antibiotics to treat stomach infections or surgery to treat intestinal problems. If the vitamin B12 level is due to a poor diet, then a person can learn how to correct the diet.

The doctor may also recommend limiting physical activity until anemia symptoms have improved.



National Heart, Lung, and Blood Institute, USA.