Anemia is a condition in which the body does not have enough red blood cells or hemoglobin. Hemoglobin is a substance in red blood cells that carries oxygen. Pernicious anemia happens when the body does not have enough of a protein made in the stomach called intrinsic factor (IF). Without enough IF, your digestive tract cannot absorb enough of the vitamin B12 that your body needs to make red blood cells. Normally, you can get enough vitamin B12 from eating foods such as meat, poultry, eggs, and dairy products. If you have pernicious anemia, you do not absorb enough vitamin B12 from your diet, and anemia develops over time.

When you have anemia, your organs may not work properly and you may feel very tired. Untreated pernicious anemia can lead to severe symptoms of anemia, including chest pain, heart failure, and permanent nervous system damage.

What are the causes?

The cause of this condition is not known. Pernicious anemia is believed to be an autoimmune disease. When you have an autoimmune disease, your body's defense system (immune system) mistakenly attacks normal cells in your body. With pernicious anemia, the immune system attacks cells that line the inside of the stomach (parietal cells). These cells secrete stomach acids and IF.

What increases the risk?

• Are older than age 40.
• Have a family history of pernicious anemia.
• Are of Northern European or Scandinavian descent.
• Have another type of autoimmune disease.

What are the signs or symptoms?

• Tiredness.
• Light-headedness.
• A sore tongue or a burning sensation on the tongue.
• A smooth red tongue.
• Shortness of breath.
• Fast heartbeat.
• Chest pain.

• Nausea or vomiting.
• Heartburn.
• Weight loss without trying.
• Diarrhea.

• Dizziness.
• Being unsteady while walking.
• Tingling or numbness of hands and feet.
• Irritability.
• Depression.
• Hallucinations or delusions.
• Loss of smell.

How is this diagnosed?

• Count the different types of blood cells (complete blood count or CBC).
• Test for different types of anemia.
• Check for proteins made by your immune system (antibodies) that attack parietal cells. Almost all people with pernicious anemia have these antibodies.
• Check your B12 level.

How is this treated?

• Injections of vitamin B12. This is the most common treatment. You will also have your blood level of B12 checked regularly. After you have a normal level of vitamin B12, and the anemia has been corrected, the injections can be given about once a month.
• Taking a pill by mouth that contains a large dose of vitamin B12.
• Using a spray that you breathe in through your nose (nasal spray). A vitamin B12 nasal spray may be used to treat people who are not able to swallow supplements.
• Long-term monitoring and regular visits to a health care provider.

If the condition is detected and treatment is started in the early stages, most people do not develop complications. Treatment reverses the condition and prevents future anemia, but it must be continued for life. Having pernicious anemia also puts you at higher risk for stomach cancer.

Follow these instructions at home:

• Take over-the-counter and prescription medicines only as told by your health care provider.
• Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
• Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if:

• You develop new symptoms.
• Your symptoms return or get worse after treatment.
• You have stomach pain.
• You feel full after eating a small meal.
• You have trouble swallowing.

Get help right away if:

• You have chest pain.
• You have a rapid heartbeat.
• You have dizziness or you faint.
• You have trouble breathing.
• You have a feeling as if your heart is skipping beats or fluttering (palpitations).
• You have pain, swelling, or redness in an arm or leg.
• You cough up blood.

These symptoms may represent a serious problem that is an emergency. Do not wait to see if the symptoms will go away. Get medical help right away. Call your local emergency services (911 in the U.S.). Do not drive yourself to the hospital.

Summary

• Pernicious anemia happens when your body cannot make enough red blood cells due to vitamin B12 deficiency.
• This condition is usually caused by an autoimmune disease that attacks stomach cells that produce intrinsic factor (IF). You need IF to absorb vitamin B12.
• Pernicious anemia symptoms may take many years to develop.
• This condition is sometimes discovered during routine blood testing.
• Treatment of this condition includes vitamin B12 replacement for life.