• (pernicious anemia) A form of anemia in which red blood cells enlarge and decrease in size due to an inability to properly absorb vitamin B12.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• (pernicious anemia) A type of anemia (low red blood cell count) caused by the body's inability to absorb vitamin B12.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• (pernicious anemia) Anemia due to poor intestinal absorption of vitamin B12 caused by defective production of intrinsic factor (a carrier protein) by the gastric mucosa.
  CRISP Thesaurus
  National Institutes of Health, 2006
• (pernicious anemia) Megaloblastic anemia caused by vitamin B-12 deficiency due to impaired absorption. The impaired absorption of vitamin B-12 is secondary to atrophic gastritis and loss of gastric parietal cells.
  NCI
  U.S. National Cancer Institute, 2021
• (pernicious anemia) Megaloblastic anemia caused by vitamin B12 deficiency due to insufficient production of intrinsic factor by gastric parietal cells, which is essential for adequate absorption of vitamin B12. It is classically characterized by weakness and fatigue, glossitis, and paresthesias.
  NICHD Pediatric Terminology
  U.S. National Cancer Institute, 2021
• A megaloblastic anemia occurring in children but more commonly in later life, characterized by histamine-fast achlorhydria, in which the laboratory and clinical manifestations are based on malabsorption of vitamin B 12 due to a failure of the gastric mucosa to secrete adequate and potent intrinsic factor. (Dorland, 27th ed)
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• Pernicious anemia is a chronic illness caused by impaired absorption of vitamin B-12 because of a lack of intrinsic factor (IF) in gastric secretions. It occurs as a relatively common adult form of anemia that is associated with gastric atrophy and a loss of IF production and as a rare congenital autosomal recessive form in which IF...
  Medscape
  WebMD, 2025
• Biermer's disease, also called acquired pernicious anemia, is a condition in which the body is unable to properly utilize vitamin B12. Because vitamin B12 is essential for the formation of red blood cells, this condition is primarily characterized by anemia (too few red blood cells). Affected people may also experience gastrointestinal...
  NIH Genetic and Rare Diseases
  National Center for Advancing Translational Sciences
• Pernicious anemia, disease in which the production of red blood cells (erythrocytes) is impaired as a result of the body's inability to absorb vitamin B12, which is obtained in the diet and is necessary for red blood cells to mature properly in the bone marrow. Pernicious anemia is one of many...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2025