Pernicious Anemia

Medically Reviewed By William C. Lloyd III, MD, FACS

What is pernicious anemia?

Pernicious anemia is a condition in which the body produces insufficient numbers of red blood cells because the intestines cannot absorb vitamin B12 properly. Vitamin B12 is essential for the production of red blood cells in the bone marrow. This disorder occurs due to low levels of a protein called intrinsic factor, which is released by stomach cells and is necessary for the absorption of vitamin B12 in the intestines.

The inability to produce intrinsic factor may be inherited or may arise from an autoimmune process, in which the body’s immune system attacks its own tissues, in this case, specialized mucosal cells in the lining of the stomach. Pernicious anemia can also develop from other conditions affecting the stomach lining, such as atrophic gastritis (inflammation and thinning of the stomach lining). Pernicious anemia is more common in people with Northern European or Scandinavian ancestry, and the average age of onset of symptoms is 60 years (Source: PubMed Health Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source ).

Pernicious anemia leads to reduced levels of oxygen in the body, which can produce generalized symptoms, such as fatigue, weakness, and shortness of breath. Left untreated, pernicious anemia can cause permanent damage to the nervous system. Fortunately, pernicious anemia can be treated successfully.

Treatment for pernicious anemia includes vitamin B12 supplementation, which is administered through injection. Oral vitamin B12 supplements are not absorbed well because patients with pernicious anemia lack adequate intrinsic factor in the stomach lining. Treatment with vitamin B12 injections can prevent the permanent neurological damage that may result from deficiency of this vitamin.

Seek prompt medical care if you experience persistent or serious symptoms of neurological damage associated with pernicious anemia, including confusion, changes in behavior or personality, loss of balance, or memory loss. You should also seek medical care for persistent symptoms of pernicious anemia, such as shortness of breath, dizziness, or fatigue.

What are the symptoms of pernicious anemia?

Symptoms of pernicious anemia include general fatigue and weakness, digestive symptoms such as constipation or diarrhea, and neurological symptoms such as confusion, depression, loss of balance, or numbness. Neurological symptoms are serious and may indicate persistent anemia that should be treated promptly.

General symptoms of pernicious anemia

Mild pernicious anemia may occur without noticeable symptoms. In moderate cases of pernicious anemia, general symptoms may include:

Digestive system symptoms of pernicious anemia

In addition to causing general symptoms, pernicious anemia can affect the digestive system and lead to symptoms including:

Symptoms that might indicate a serious condition

In some cases, pernicious anemia can cause serious neurological problems that should be promptly evaluated. Seek prompt medical care if you, or someone you are with, have any of these serious neurological symptoms of pernicious anemia including:

What causes pernicious anemia?

Pernicious anemia is caused by the lack of a protein called intrinsic factor. This protein, which is produced by cells in the stomach lining, is essential for proper absorption of dietary vitamin B12 in the intestines. Low levels of intrinsic factor are often the result of an autoimmune condition, in which the body produces antibodies that attack its own stomach cells. Rarely, infants are born lacking ability to make intrinsic factor, a condition known as congenital pernicious anemia.

Pernicious anemia can also develop as a result of atrophic gastritis, a condition that damages the lining tissues of the stomach, impairing their ability to produce intrinsic factor.

What are the risk factors for pernicious anemia?

A number of factors increase the risk of developing pernicious anemia. Not all people with risk factors will get pernicious anemia. Risk factors for pernicious anemia include:

  • Family history of autoimmune disorders
  • Family history of pernicious anemia
  • Northern European or Scandinavian ancestry

Reducing your risk of pernicious anemia

The deficiencies of intrinsic factor that cause pernicious anemia are due to inherited or autoimmune causes and usually cannot be prevented. However, you can reduce your risk of developing anemia or neurological complications by following your treatment plan and receiving vitamin B12 injections as prescribed by your health care provider.

How is pernicious anemia treated?

For most patients with pernicious anemia, the condition is readily treated, and the prognosis is excellent. Treatment of pernicious anemia involves the administration of vitamin B12 injections, typically on a monthly basis. In some cases, taking very high doses of vitamin B12 supplements by mouth may be effective, although in general, low levels of intrinsic factor limit the absorption of oral vitamin B12. Blood transfusions are rarely needed, but they may be used in severe cases.

What are the potential complications of pernicious anemia?

Although medical intervention for pernicious anemia is generally very effective, complications may occur in cases that are left untreated for periods longer than six months. In these cases, permanent neurological complications can occur. Persistent anemia can also cause heart complications, such as rapid or irregular heartbeat.

People with pernicious anemia have an increased risk of developing stomach polyps (benign growth of tissue) and stomach cancer.

You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of pernicious anemia include:

  • Dementia
  • Depression
  • Increased risk of stomach cancer
  • Nerve problems that cause pain, numbness or tingling
  • Problems with balance or coordination
  • Stomach polyps (benign growth of tissue)
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 30
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