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Pernicious anemia

Macrocytic achylic anemia; Congenital pernicious anemia; Juvenile pernicious anemia; Vitamin B12 deficiency (malabsorption); Anemia - intrinsic factor; Anemia - IF; Anemia - atrophic gastritis; Biermer anemia; Addison anemia

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types of anemia.

Pernicious anemia is a decrease in red blood cells that occurs when the intestines cannot properly absorb vitamin B12.

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Megaloblastic anemia - view of red blood cells

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Causes

Pernicious anemia is a type of vitamin B12 anemia. The body needs vitamin B12 to make red blood cells. You get this vitamin from eating foods such as meat, poultry, shellfish, eggs, and dairy products.

A special protein, called intrinsic factor (IF), binds vitamin B12 so that it can be absorbed in the intestines. This protein is released by cells in the stomach. When the stomach does not make enough intrinsic factor, the intestine cannot properly absorb vitamin B12.

Common causes of pernicious anemia include:

In rare cases, pernicious anemia is passed down through families. This is called congenital pernicious anemia. Babies with this type of anemia do not make enough intrinsic factor. Or they cannot properly absorb vitamin B12 in the small intestine.

In adults, symptoms of pernicious anemia are usually not seen until after age 30. The average age of diagnosis is age 60.

You are more likely to develop this disease if you:

Certain diseases can also raise your risk. They include:

Pernicious anemia can also occur after gastric bypass surgery.

Symptoms

Some people do not have symptoms. Symptoms may be mild.

They can include:

If you have a low vitamin B12 level for a long time, you can have nervous system damage. Symptoms can include:

Exams and Tests

The health care provider will perform a physical exam. Tests that may be done include:

Treatment

The goal of treatment is to increase your vitamin B12 level:

Outlook (Prognosis)

Most people often do well with treatment.

It is important to start treatment early. Nerve damage can be permanent if treatment does not start within 6 months of symptoms.

Possible Complications

People with pernicious anemia may have gastric polyps. They are also more likely to develop gastric cancer and gastric carcinoid tumors.

People with pernicious anemia are more likely to have fractures of the back, upper leg, and upper forearm.

Brain and nervous system problems may continue or be permanent if treatment is delayed.

A woman with a low B12 level may have a false positive Pap smear. This is because vitamin B12 deficiency affects the way certain cells (epithelial cells) in the cervix look.

When to Contact a Medical Professional

Call your provider if you have symptoms of vitamin B12 deficiency.

Prevention

There is no known way to prevent this type of vitamin B12 anemia. However, early detection and treatment can help reduce complications.

Related Information

Vitamin B12
Anemia
Endocrine glands
Type 1 diabetes
Hypoparathyroidism
Addison disease
Hypopituitarism
Graves disease
Chronic thyroiditis (Hashimoto disease)
Myasthenia gravis
Absent menstrual periods - secondary
Vitiligo
Celiac disease - sprue
Pulmonary tuberculosis
Stomach cancer
Pap test

References

Antony AC. Megaloblastic anemias. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 39.

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.

Elghetany MT, Schexneider KI, Banki K. Erythrocytic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 32.

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Review Date: 1/19/2018  

Reviewed By: Richard LoCicero, MD, private practice specializing in hematology and medical oncology, Longstreet Cancer Center, Gainesville, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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