What is Pernicious Anemia?

Anemia is a condition characterized by the reduced production of healthy blood cells. An important function of the red blood cells is to carry oxygen to the tissues in the body; hence a decrease in these cells reduces the body’s oxygen supply of oxygen. Pernicious anemia is condition that results in a lack of vitamin B12 due to the low absorption and further results in production of unhealthy red blood cells.

What Causes Pernicious Anemia?

People with pernicious anemia are not able to absorb vitamin B12 from the food taken. This is due to the absence of a specific protein called the intrinsic factor which is responsible for the absorption of vitamin B12. This protein released by the parietal cells of the stomach, binds with the vitamin B12 in the food taken to form a complex, and this complex is later absorbed in the intestine. The absorbed vitamin B12 plays a role in the production of healthy red blood cells.

The reasons for the malabsorption of vitamin B12 could be

  • A weakened stomach lining (atrophic gastritis)
  • An autoimmune condition where the body considers the actual intrinsic factor protein or the cells in the lining of your stomach that make it as alien to the body and attacks them

When the condition is present at birth, it is known as congenital pernacious anemia; the babies do not have sufficient intrinsic factor necessary to absorb vitamin B12.

This condition may be associated with other auto immune conditions like type 1 diabetes, hypoparathyroidism, Addison’s disease.

What are the Symptoms and Signs of Pernicious Anemia?

The most common form of pernicious anemia is the adult form that is more commonly seen among women. The symptoms of pernicious anemia in adults are seen after 30 years. When seen in infants from 4 to 28 months, it is known as juvenile pernicious anemia. The symptoms and signs of pernicious anemia include:

  • Weakness, fatigue, shortness of breath, rapid heart rate, confusion
  • Jaundice, unhealthy pale appearance, bleeding of gums, smooth and beefy tongue
  • Tingling and numbness of hand and feet, unsteadiness while walking
  • PICA (desire to eat ice or other non-food things), loss of appetite, diarrhea
  • Impaired reflexes and coordination movements, depression and increased irritability
Symptoms and Signs of Pernicious Anemia

What is The Difference between Anemia / Vitamin b-12 Deficiency and Pernicious Anemia?

Anemia (of which pernicious anemia is a type), occurs when the intrinsic factor is at normal levels but the levels of vitamin B12 in the body are still low due to other reasons. The occurrence of these low levels of vitamin B12 is rare as the vitamin is usually stored in the liver where it can last for 3-5 years.

The low levels are commonly seen among people who eat a diet that is deficient in vitamin B12. Vitamin B12 rich foods include:

  • Meat: beef, liver, poultry, fish
  • Eggs and dairy products
  • Foods fortified with vitamin B12

Apart from a low level of healthy blood cells in anemia, an abnormally enlarged spleen and liver, diarrhea or constipation and a reduced appetite are also seen.

Low vitamin B12 levels also can occur due to malabsorption of the vitamin in the intestine. Possible causes of malabsorption include:

  • Surgical interventions on the gastrointestinal tract
  • Certain medicines that can alter the bacterial growth of necessary gut bacteria
  • Certain gastrointestinal conditions like Celiac disease, Crohn’s disease

What are the Risks Factors of Pernicious Anemia?

The risk factors for pernicious anemia include:

  • Being a North European or Scandinavian
  • Having a family history of the condition - the genetic link of this condition has been identified on chromosomes 10, 11 and 14.
  • Having undergone prior abdominal surgeries involving the gastrointestinal tract or digestive disorders
  • Presence of other autoimmune conditions like type 1 diabetes, Graves disease, Myasthenia Gravis, Addison disease hypoparathyroidism and hypopituitarism

How do you Diagnose Pernicious Anemia?

Diagnosis of pernicious anemia requires a complete history with dietary patterns and physical examinations. The tests that are conducted include:

  • Complete blood count
  • Peripheral blood smear
  • Vitamin B12 levels
  • Reticulocyte count: it measures the number of young red blood cells
  • Schilling test: Intestinal ability to absorb Vitamin B12 is checked
  • Lactose Dehydrogenase levels (LDH), Methylmalonic acid levels (MMA)
  • Antibodies against Intrinsic Factor(IF)
  • Bone marrow biopsy is done to check whether it is healthy and producing red blood cells normally
Diagnosis of Pernicious Anemia

How do you Treat Pernicious Anemia?

Treatment of pernicious anemia has to be done as early as possible. The treatment should correct the status of anemia of the patient, be specific to the cause and manage or prevent any complications. Vitamin B12 is given as cobalamin supplements which can be in the form of cyanocobalamin (CN-Cbl), hydroxocobalamin (OH-Cbl) or methylcobalamin. The treatment modalities include:

  • Vitamin B12 shots or injections are available for intramuscular administration in case of severe pernicious anemia; shots are usually given every day or weekly till the blood B12 levels rise; once the levels are normal the shots can be given once a month
  • Oral supplementation of vitamin B12 in the form of pills is given for less severe pernicious anemia; vitamin B12 nasal spray is also available for patients who have trouble in swallowing pills
  • Maintenance doses of vitamin B12 will be required; hence close monitoring of the patients is done
  • Genetic counseling of pernicious anemia patients may help the families
Treatment for Pernicious Anemia

What are the Complications of Pernicious Anemia?

The complications of pernicious anemia if left untreated include:

Gastrointestinal complications can lead to gastric polyps that further develop into cancerous lesions or carcinoid tumors.

Neurological complications lead to nerve and brain damage, dementia, and in coordinate movements (ataxia).


  1. Pernicious Anemia - (https://www.nhlbi.nih.gov/health-topics/pernicious-anemia)
  2. Anemia - Symptoms and Causes - (https://www.mayoclinic.org/diseases-conditions/anemia/symptoms-causes/syc-20351360)
  3. What is Anemia Pernicious - (https://rarediseases.org/rare-diseases/anemia-pernicious/)

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