What is Pernicious Anemia?

Pernicious Anemia Video

Pernicious anemia is an autoimmune disorder in which the body doesn’t produce enough healthy red blood cells due to its inability to absorb vitamin B-12.

“Pernicious” actually means “deadly” and is used because it was once considered a deadly disease due to the lack of available treatment. However, failure to diagnose & treat in time can result in severe neurologic complications, leading to death.

The disease was first clearly described in 1849 by Thomas Addison, from which it acquired the common name of Addison’s anemia. It may also be referred to as Vitamin B-12 deficiency.


– Pernicious anemia is caused by a lack of intrinsic factor (IF) in the stomach, which causes B-12 deficiency. Intrinsic factor is a protein produced by the parietal cells of the gastric mucosa (stomach lining) that is necessary for the absorption of vitamin B-12 later on in the small intestine.
– Vitamin B-12 is not produced by the body & must be obtained from the diet.
– B-12 is naturally found in animal products including meat, poultry, fish, eggs, and dairy products. Fortified cereals and nutritional supplements are another source.

When vitamin B-12 is consumed, it travels to the stomach where it binds with intrinsic factor (IF), and the two are then absorbed in the last part of the small intestine.

In most cases of pernicious anemia, the body’s immune system attacks and destroys the cells that produce IF in the stomach. When these cells are destroyed, the body can’t make IF and therefore can’t absorb vitamin B-12.

Sometimes other causes of vitamin B-12 deficiency, such as poor diet, are confused with pernicious anemia. However, pernicious anemia is strictly caused by a lack of IF, whether that be due to an autoimmune disorder, gastrectomy or gastric bypass surgery, or a genetic defect in which a child is born not making IF.

Without enough B12, the body will produce macrocytes (abnormally large red blood cells) which may not be able to enter the bloodstream from the bone marrow, resulting in a decrease in oxygen-carrying RBCs in the bloodstream.

Pernicious anemia is sometimes called megaloblastic anemia because of the abnormally large size of RBCs produced.

It is not preventable & occurs in about 1 in 1000 people, usually between the ages of 40-70 years. Patients with pernicious anemia often have other autoimmune disorders as well as a 2-3 times increased risk of gastric cancer.

Symptoms and Diagnosis

The signs & symptoms of pernicious anemia are usually subtle & vague, and many are due to anemia itself.

There is a triad of classic symptoms including:

Weakness / fatigue
Sore tongue (glossitis)
Skin tingling (paresthesia)
However, these are not always seen in all patients.

There are many other common symptoms, including:

– Slight jaundice
– Pale skin with dark circles around the eyes
– Thinning & early graying of the hair & brittle nails
– Headaches
– Low-grade fever
– Depressive mood
– A swollen, red, smooth tongue
– Sores at the corner of the mouth (angular cheilitis)
– Loss of appetite / weight loss
– Pica (desire to eat ice or other non-food things, dirt or paper)
– Tachycardia / chest pain / evidence of CHF
– Altered blood pressure
– Shortness of breath
– Nerve damage (can be permanent if treatment not started within 6 months of symptoms)

Severe pernicious anemia can lead to neurological symptoms, including:

An unsteady gait, clumsiness
Stiffness & tightness in the muscles
Numbness in arms & legs
Dementia, psychotic depression, psychosis
Progressive lesions of the spinal cord
Death in serious cases

DIAGNOSIS of pernicious anemia involves several tests:

CBC (complete blood count)
Blood smear
Vitamin B12 deficiency blood test
Intrinsic factor (IF) antibody blood test
Evaluation of gastric secretions
Stomach biopsy to look for cell damage
Schilling test, however it is no longer widely used

Treatment for pernicious anemia involves administration of vitamin B-12 (either cyanocobalamin or hydroxocobalamin), which will stop anemia-related symptoms and neurological deterioration. If neurological problems are not advanced, complete remission of all symptoms will occur as long as B-12 is supplemented.

Standard treatment of B-12 is usually by intramuscular (IM) injection, but oral doses also appear to be effective. Other methods include sublingual & intranasal treatment, and experimental transdermal patches.

Patient follow-up is required to make sure they respond to therapy & that they continue to receive therapy for the rest of their lives.

B-12 therapy resolves the anemia, however, it does not cure the chronic inflammation of the stomach mucosa, which can progress to gastric cancer.

Treatment for pernicious anemia.

Vitamin B-12 (cyanocobalamin or hydroxocobalamin):


*Treatment is lifelong

When caring for the patient with pernicious anemia, the nurse should…

– Remind patients that their family members are at a greater risk of developing the disease & should be monitored for anemia and mental or neurological symptoms.

– Teach the patient about eating a diet rich in vitamin B-12.

– Instruct strict vegetarians, particularly those who do not eat eggs, milk, or meat to take supplementary B-12 for their lifetime, especially during pregnancy and breastfeeding.


Let’s take a look at a quick review of pernicious anemia…

– The body requires vitamin B-12 and the protein called intrinsic factor (IF) to make red blood cells.

– Pernicious anemia is an autoimmune disorder in which the body doesn’t produce enough healthy red blood cells due to its lack of IF and inability to absorb vitamin B-12.

– The three symptoms seen most often include weakness/fatigue, sore tongue, & skin tingling. If not treated, symptoms can become more severe, leading to death.

– Treatment involves lifelong administration of B-12, but a person that is well-treated can live a healthy life.


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by Mometrix Test Preparation | This Page Last Updated: January 25, 2024