Symptoms and Signs of Pernicious Anemia (Vitamin B12 Deficiency)

Medical Author:
Medically Reviewed on 2/9/2022

Doctor's Notes on Pernicious Anemia (Vitamin B12 Deficiency)

Pernicious anemia (vitamin B12 deficiency) is anemia (reduced number of red blood cells) due to the body's inability to absorb vitamin B12 from the GI tract. Signs and symptoms may occur slowly over the years and are nonspecific (pernicious). They include

  • numbness,
  • tingling,
  • weakness,
  • clumsiness,
  • lack of coordination,
  • impaired memory, and
  • possibly personality changes.

Both sides of the body are affected with the body's legs more than the arms. Severe symptoms include

Other signs and symptoms may occur with more severe anemia and include

  • pale skin,
  • heart murmurs,
  • fast and/or irregular heartbeats,
  • enlarged heart,
  • heart failure, and
  • shortness of breath.

In addition, pernicious anemia is a form of megaloblastic anemia that is characterized by abnormally large red blood cells formed by the bone marrow when B12 and folate levels are low.

The cause of most incidences of pernicious anemia is believed to be an autoimmune problem where the immune system attacks the stomach lining (intrinsic factor protein) necessary for B12 absorption by the body. Other associated causes may be genetics, the suspected cause of rare congenital pernicious anemia, or bacterial overgrowth in the GI tract.

What Are the Treatments for Pernicious Anemia?

Treatments for pernicious anemia are simple; replace the low levels of vitamin B12 orally or by injections. If identified and is treatable, address any underlying causes (for example, lack of intrinsic factor, bacterial overgrowth in the GI tract).

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.