Pernicious anemia: Failure of vitamin B12 absorption

Pernicious anemia is a congenital or acquired autoimmune condition in which the body does not have enough red blood cells. These normally provide oxygen to body tissues. Pernicious anemia causes a reduction in red blood cells because the intestines are unable to properly absorb vitamin B12 due to a number of conditions. This leads to symptoms of anemia such as fatigue and a lemon-yellow appearance. Neurological signs also occur with pernicious anemia, such as tingling and numbness in the hands and feet. The treatment of this disease consists of administering vitamin B12. The prospects for most patients are excellent. But if the patient does not receive timely diagnosis and treatment, permanent neurological damage sometimes occurs.

  • Epidemiology autoimmune disorder
  • Causes: Failure of absorption of vitamin B12
  • Risk factors for pernicious anemia
  • Symptoms of anemia and neurological signs
  • Diagnosis and examinations
  • Treatment via vitamin B12
  • Prognosis is usually good
  • Complications

Epidemiology autoimmune disorder

This disease is common in the elderly. Approximately 1 in 8,000 people over 60 suffer from pernicious anemia. This form of anemia occurs in all breeds, but is more common in people with blonde hair and blue eyes (eye color), and people who have blood type A. Patients of Scandinavian or Northern European descent or patients with a family history of the condition are also more likely to develop pernicious anemia. Women are also more likely than men to be affected by the blood disorder. In adults, symptoms of the blood disorder only become apparent after the age of thirty, but the average age of diagnosis is sixty years. A congenital form of pernicious anemia is also possible; The problems already arise at birth.

Causes: Failure of absorption of vitamin B12

Pernicious anemia is an autoimmune condition in which there are insufficient red blood cells because the intestines cannot absorb enough vitamin B12 (leading to a vitamin B12 deficiency). The body does need vitamin B12 to produce red blood cells. People get this vitamin by eating certain foods such as meat, poultry, shellfish, eggs and dairy products. A special protein called intrinsic factor (IF) helps the intestines absorb (absorb) vitamin B12. Cells in the stomach release this protein. When the stomach does not produce enough intrinsic factor, the intestines are not able to absorb vitamin B12 properly.

Common causes of pernicious anemia include:

  • a weakened stomach wall (atrophic gastritis)
  • an autoimmune condition in which the body’s own immune system attacks the protein intrinsic factor or the cells in the lining of the stomach (that produce IF). In very rare cases, pernicious anemia has a familial origin; then there is congenital pernicious anemia. Babies with such anemia do not produce enough intrinsic factor, or else they do not absorb enough vitamin B12 in the small intestine.

Risk factors for pernicious anemia

If the patient has one of the following conditions, there is a higher risk of developing pernicious anemia:

  • Addison’s disease (insufficient production of hormones by adrenal glands)
  • Graves’ disease (autoimmune disorder with overproduction of thyroid hormones)
  • diabetes mellitus type 1 (diabetes)
  • Hashimoto’s thyroiditis (chronic inflammation of the thyroid gland mainly in women, caused by autoimmunization against thyroglobulin)
  • hypoparathyroidism (underactive parathyroid gland(s))
  • hypopituitarism (lack of hormones caused by the pituitary gland)
  • myasthenia gravis (severe muscle weakness due to a disorder in the transmission of nerve impulses with facial symptoms = weakness of the face, limbs and eyes)
  • secondary amenorrhea (no menstrual period for at least six months)
  • testicular dysfunction
  • vitiligo (skin condition with white spots on the skin)

Symptoms of anemia and neurological signs


The onset of pernicious anemia is insidious, with a gradual increase (over many years) in symptoms of anemia, although some patients show no or only mild symptoms. Patients sometimes develop a lemon-yellow color due to a combination of pallor and mild jaundice caused by excessive breakdown of hemoglobin. A red, swollen, painful tongue (glossitis) and stomatitis (inflammation of the mucous membrane in and around the mouth) are sometimes present. Other signs of anemia include: difficulty concentrating, diarrhea or constipation, a loss of appetite, the desire to eat inedible things (pica), shortness of breath (usually during exertion), fatigue, a lack of energy or dizziness when standing up or during exertion .

Neurological symptoms

With a long-term very low vitamin B12 level (less than 60 ng / L or 50 pmol / L), damage to the nervous system occurs. This neurological damage sometimes occurs in patients who clinically show no signs of anemia. Patients present with symmetrical paresthesias (tingling) and numbness in the fingers and toes, and progressive muscle weakness and ataxia (balance and coordination problems). These problems may lead to a spinal cord injury (spinal cord injury: damage to the spinal cord). Dementia, confusion, depression, psychiatric problems, hallucinations, delusions, and optic atrophy (death of the optic nerve) are hallmarks of a vitamin B12 deficiency.

Diagnosis and examinations

Diagnostic research

The patient receives a physical examination. However, in the case of pernicious anemia, the doctor must perform additional tests to make a diagnosis. For example, he performs a complete blood test and occasionally a bone marrow puncture. However, a bone marrow examination is only necessary if the diagnosis is unclear. Pernicious anemia is one of two major types of “macrocystic” or “megaloblastic” anemia. These terms refer to anemia in which the red blood cells are larger than normal, which is also evident from the blood test. The other type of megaloblastic anemia is anemia caused by a deficiency of folic acid.

Differential diagnosis

The doctor wants to use the blood test and sometimes also the bone marrow test to rule out various other conditions, such as:

  • achlorhydria (absent hydrochloric acid in stomach with vitamin deficiencies)
  • alcoholic hepatitis
  • alcoholic fatty liver
  • anemia
  • atrophic gastritis (infection and atrophy of the stomach)
  • bone marrow failure (insufficient production of blood cells)
  • iron deficiency anemia (ferriprieve anemia)
  • cirrhosis
  • celiac disease (stomach and intestinal problems due to eating gluten)
  • a myeloproliferative disease
  • folic acid deficiency
  • hemolytic anemia (premature breakdown of red blood cells)
  • Zollinger-Ellison syndrome (too much acid released by the stomach)
  • hyperthyroidism (overactive thyroid)
  • hypothyroidism (underactive thyroid gland)
  • immune thrombocytopenic purpura (ITP)
  • stomach cancer
  • macrocytosis (anemia with large red blood cells)
  • malabsorption (problems with nutrient absorption)
  • megaloblastic anemia
  • unconjugated hyperbilirubinemia (increased bilirubin levels in the blood)
  • tropical thrush (intestinal disease present in tropical areas)

Yogurt is a good source for the absorption of vitamin B12 in the body / Source: HealthGauge, Flickr (CC BY-2.0)

Treatment via vitamin B12

The doctor increases the presence of vitamin B12 in the patient’s body through a monthly injection. In patients with a severe deficiency, more injections are sometimes required initially. Some patients also take oral (by mouth) vitamin B12 supplements. A certain type of vitamin B12 can also be given through the nose. In addition, the patient is given nutritional tips and advice to consume foods that contain vitamin B12. The following foods are good:

  • eggs and dairy products (such as milk, yogurt and cheese)
  • breakfast cereals with added vitamin B12
  • meat such as beef, liver, poultry and fish
  • foods fortified with vitamin B12, such as soy-based drinks and vegetarian burgers

Prognosis is usually good

Most patients often respond well to treatment, but early treatment is necessary. Neurological changes that remain untreated for a long time (six months after the onset of symptoms) are in most cases irreversible.


Patients with pernicious anemia sometimes have gastric polyps (benign growths on the stomach lining). This creates an increased risk of stomach cancer and malignant stomach tumors. Furthermore, permanent neurological damage occurs if the doctor does not diagnose and treat the patient in a timely manner. Finally, in women with a low B12 level, a false positive smear sometimes appears. Oily urine (due to blocked lymphatic vessels in the kidneys) is another possible complication.

read more

  • Anemia (deficiency of red blood cells): Types and causes
  • Vitamin B12 Deficiency: Symptoms & Treatment of Deficiency
  • Anemia (anemia): Types of red blood cell deficiency
  • Vitamins and minerals: Function, deficiency & excess intake
Pernicious anemia: Failure of vitamin B12 absorption
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