Symptoms and Signs of Pernicious Anemia
(Vitamin B-12 Deficiency)

Medical Author:
Medically Reviewed on 3/11/2019

Doctor's Notes on Pernicious Anemia
(Vitamin B-12 Deficiency)

Pernicious anemia (vitamin B-12 deficiency) is anemia (reduced number of red blood cells) due to the body’s inability to absorb vitamin B-12 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 spastic movements, paraplegia and incontinence of urine and feces. Other signs and symptoms may occur with more severe anemia; 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 B-12 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 B-12 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.

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