Pernicious anemia: lack of vitamin b12 and symptoms


What is pernicious anemia?

Pernicious anemia is an autoimmune disease in which the body is unable to produce an adequate amount of red blood cells due to a lack of vitamin B12/cyanocobalamin.

To absorb vitamin B12, a glycoprotein called intrinsic factor is required.

In a healthy immune system, antibodies are responsible for finding bacteria and viruses. As a result, they mark the pathogens that need to be destroyed.

In an autoimmune disease such as PA, the antibodies can no longer distinguish between healthy and diseased tissue.

In this case, they destroy cells of the intestinal mucosa, secreting intrinsic factor.

The cells of the inner stomach wall also produce hydrochloric acid (HCl), which is used to digest and sterilize the food ingested.

Pernicious anemia also causes a reduction in the production of HCl.

The consequence is also the multiplication of bacteria.

Pernicious anemia is characterized by a deficiency of B12 and folic acid.

Vitamin B12:

  • Is necessary for the proper functioning of the nervous system, because it intervenes in the synthesis of myelin (outer protective layer of nerves) – vitamins B12 (April 22, 2014).
  • Contributes to the production of DNA and RNA, the genetic material of the body.
  • Together with vitamin B9 (folic acid), it intervenes in the production of red blood cells.
  • Vitamins B12, B6 and B9 work together to control blood levels of the amino acid homocysteine. High homocysteine levels are found in patients with heart disease.

In addition, vitamin B12 plays a fundamental role in mitochondrial glucose metabolism [Kerns J.C., Arundel C., Chawla L.S. Thiamine deficiency in people with obesity. Adv. Nutr. Int. Rev. J. 2015;6:147–153], degli acidi grassi e degli amminoacidi.

A neurological disorder characterized by the loss of myelin (nerve sheath) is often accompanied by pernicious anemia.

Possible causes are:

  1. Absence of a substance called methionine, obtained from homocysteine.
  2. Decrease in succinylCoA, which causes the formation of abnormal fats that alter myelin.

Symptoms of pernicious anemia

  1. Addison’s anemia;
  2. Addison-Biermer anemia;
  3. Pernicious Addison’s anemia;
  4. Primary form of anemia.

Pernicious anemia is a type of anemia:

  • Macrocytic (that is, with an MCV greater than 95 fl) due to the large dimensions of red blood cells.
  • Megaloblastic, which means that the red blood cells do not mature because the nucleus does not develop while the cytoplasm develops.

This disease is called pernicious anemia (which means “extremely harmful”), because before the main causes were discovered, it was considered a fatal disease, especially since there were no specific therapies.

Pernicious anemia is more common in the elderly.

Like most autoimmune diseases, it is often accompanied by other pathologies:

  • Addison’s disease;
  • Chronic thyroiditis;
  • Graves’ disease;
  • Hypoparathyroidism;
  • pituitary insufficiency;
  • myasthenia gravis;
  • Secondary amenorrhea;
  • type 1 diabetes;
  • testicular dysfunction;
  • Vitiligo.

Causes of megaloblastic anemia

Often the causes of vitamin B12 deficiency are confused with PA.

Pernicious anemia is, strictly speaking, an autoimmune disease that occurs due to the absence of intrinsic factor.

It is also observed in children with a genetic defect that prevents intrinsic factor production.

The various causes of megaloblastic anemia are:

  1. Too long use of medication and antibiotics (methotrexate, azathioprine, etc.);
  2. Poor absorption or malabsorption of folate (folic acid is an active form of folates).
  3. Loss or increase in folic acid requirements (for example, in neoplasia, kidney or heart failure)
  4. Autoimmune chronic atrophic gastritis damages the gastric mucosa and reduces the ability to produce intrinsic factor.
  5. This disease can be the result of infection by Helicobacter pylori
  6. Surgical intervention on the stomach may involve the removal of part or all of the stomach. It is also performed for weight loss. After the operation, vitamin B12 can no longer be absorbed from food because intrinsic factor can no longer be produced.
  7. A diet low in cobalamin, for example strictly vegetarian or low in vitamin B12 due to alcoholism. The main sources of the vitamin of group B are animal foods such as eggs, fish, meat, milk and other dairy products.
  8. Intestinal diseases such as Infections and Crohn’s disease that interfere with the absorption of vitamin B12.
  9. A rare genetic disease (hereditary), characterized by lack of production of intrinsic factor in children.

Symptoms of pernicious anemia

PA progresses very slowly, the symptoms are difficult for patients to recognize because they are used to a certain feeling of discomfort.

The first and also most common symptoms of pernicious anemia are:

  1. anaemia – 30-60% of cases,
  2. inflammation of the tongue and gastrointestinal disorders – 15% of cases,
  3. Paralysis and neurological symptoms – 10-28% of cases.

Those who suffer from anemia do not produce enough red blood cells and their body cells receive an insufficient amount of oxygen.

Hematocrit and hemoglobin are decreased. Thus, one of the main symptoms is fatigue.

According to the NIH (National Heart, Lung, and Blood Institute), symptoms include:

  • Weakness;
  • shortness of breath and dizziness (fainting);
  • If the anaemia is severe or severe, the result may be angina pectoris (chest pain), headache and leg pain (intermittent claudication);
  • tongue redness,
  • Weight loss
  • Jaundice
  • Diarrhoea.

Some people with vitamin B12 deficiency have neurological symptoms:

  1. change in the sense of touch;
  2. Decreased vibration sensation (inability to feel the vibrations of a tuning fork);
  3. tingling sensation on the hands and feet,
  4. Myasthenia;
  5. difficulty walking and coordination;
  6. Mental health problems such as memory loss, confusion, and depression.

Pernicious anemia can be dangerous because it is a risk factor for a stomach tumor.

Complications of pernicious anemia

Usually, affected people feel weak and tired because of the lack of oxygen in the body. If left untreated, this anemia can lead to serious problems in various organs such as the heart, nerves and digestive system.


The heart is forced to work more because of the provision of oxygen to the tissues and other organs. The increased work can cause:

  1. heart enlargement,
  2. Tachycardia
  3. Arrhythmia
  4. Heart murmur
  5. Heart failure.

Heart disease caused by cobalamin deficiency occurs because the body’s own concentration of a chemical substance called homocysteine is increased.

This substance can increase the risk of stroke or heart attack.


Nerve cells can be damaged by the lack of vitamin B12. This causes neurological symptoms, such as:

  1. Numbness
  2. tingling sensation on the hands and feet,
  3. loss of balance,
  4. difficulty walking,

Low levels of cobalamin can alter vision, smell and taste.

They can also lead to mental changes such as:

  1. Confusion
  2. Amnesia.

Digestive system

The lack of vitamin B12 can affect the surface of the tongue and cause thinning or shrinkage of the stomach lining.

This increases the risk of developing a stomach tumor.

In pregnancy, an untreated vitamin B12 deficiency can lead to premature birth, low birth weight or, in certain cases, congenital defects.

Diagnosis of pernicious anemia

The diagnosis of PA is based on some research such as:

  1. Complete blood count (RBC);
  2. vitamin B12 deficiency;
  3. intrinsic factor deficiency;
  4. Evaluation of the extent of gastric damage.

The examination of the complete blood count shows the values of:

  • Hemoglobin, a protein that binds oxygen and transports it through the blood.
  • Hematocrit, which is used to measure the volume of blood in the erythrocytes.

Reference values for hemoglobin in the blood are:

  1. Adult male – from 12.4 to 18,
  2. Adult female – from 11.7 to 16.

Vitamin B12 levels are measured by a blood test.

Low levels indicate a deficiency of this vitamin.

Often the LDH (lactate dehydrogenase) is very high, while the pepsinogen can be lowered.

Uric acid may be elevated.

Usually reticulocytes, leukocytes and platelets are lowered.

The amount of iron and direct bilirubin are too high.

Damage to the gastric mucosa can be easily diagnosed by a biopsy.

The biopsy consists of a sample of cells taken from the stomach.

Then the cells are examined in the laboratory for any damage.

deficit of intrinsic factor can be detected by a blood test.

The blood samples are tested for antibodies against:

  • intrinsic factor,
  • Gastric mucosal cells.

Schilling test

Nowadays, the test is not done often, but it can be important to find out the cause of a vitamin B12 deficiency.

It is used to understand the extent of malabsorption of vitamin B12 after diagnosis of megaloblastic anemia.

It consists of:

  1. saturation of vitamin B12 deposition in the liver by administering a high amount of vitamins through the vein,
  2. After that, the patient must drink radiolabeled vitamin B12.

If the liver deposits are saturated, at least 24% of the labeled vitamin B10 passes through the urine in a healthy person in the first 12 hours.

If the amount in the urine is lower, intrinsic factor deficiency is possible. Then the test is repeated, in which an intrinsic factor is also administered.

If B12 is found in sufficient quantities in the urine, this may indicate pernicious anemia.

If the level is still low, the patient probably has absorption problems in the area of the ileum (small intestine).

In differential diagnosis, it is necessary to exclude:

  1. thyroid disorders such as hypothyroidism,
  2. Cirrhosis
  3. Alcoholism
  4. Some medications, for example, antiviral.
  5. In the elderly. According to a study by Fiona O’Leary et al. (Discipline of Nutrition and Metabolism, School of Molecular Bioscience, University of Sydney, NSW 2006, Australia), vitamin B12 deficiency often exists due to reduced hydrochloric acid production in the stomach.

Treatment of pernicious anemia

The doctor treats pernicious anemia by supplementing vitamin B12, which the body lacks.

At the initial stage of pernicious anemia can be treated with tablets and injections of vitamin B12.

The prescribed dose is generally 100 μg intramuscularly once a month in the most severe cases.

For people who have difficulty swallowing tablets, a nasal gel or vitamin B12 spray is available on the market, which restores normal levels.

Nutritional supplements containing vitamin B12 in the form of oral or sublingual tablets are very common and available in pharmacies.

However, these tablets should only be taken by prescription.

Vitamin B12 deficiency can be partially compensated by folic acid integrators. This vitamin can improve blood cell levels, but it is not enough to repair nerves, which continue to deteriorate.

Natural remedies for pernicious anemia

There are no plants that can be used to treat this disease, but a healthy diet can help cure the conditions that cause damaging pernicious anemia.

The body needs plenty of fruits, vegetables, seeds and other plants to live, but also animal foods that contain vitamin B12:

  1. Eggs
  2. Meat
  3. Fish
  4. Milk and dairy products.

Dairy, red meat and pork can promote the development of many diseases, even serious diseases.

It is therefore particularly recommended that:

  1. Fish
  2. Eggs
  3. White meat (chicken and turkey).

Prognosis of pernicious anemia

In general, Biermer’s anemia can be easily treated by injections or vitamin B12 tablets.

Nevertheless, some people may suffer permanent damage to the nerves before the diagnosis of this condition and the start of therapy have taken place.

The doctor may order regular cancer screenings from the moment this anemia increases the likelihood of stomach cancer (or gastrointestinal cancer).

Those who receive the appropriate therapy can live normally, as they are completely cured.

Symptoms such as memory loss, fatigue, etc. may persist depending on the phase in which the disease was diagnosed.

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