Glossary of Medical Terms
Pernicious anemia (PA)
An anemia that results from a deficiency of vitamin B-12. A common cause of PA is a lack of intrinsic factor (IF), a protein produced by cells in the stomach, which is necessary for the absorption of vitamin B-12. Stomach cells may not make IF for one of several reasons: surgery that has removed part of the stomach, chronic gastritis, or normal aging. Because both nerve cells and red blood cells need B-12, PA can cause various symptoms. It usually develops slowly, over a period of years. PA can run in families and is more common in people of northern European or African descent. PA is frequently associated with autoimmune diseases such as autoimmune thyroid disease (Graves' and Hashimoto's) and Addison's disease. PA is also associated with an increased risk for stomach cancer. Untreated, PA can lead to irreversible damage to the nervous system. It can be treated and damage prevented by monthly injections of B-12.