pernicious anemia; autoimmune gastritis
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Etiology
- autoimmune
- associated autoimmune diseases
Epidemiology
- most common cause of vit B12 deficiency in temperate climates
- occurs most frequently in patients of northern European descent & African Americans
- much less common in southern Europeans & Asians
- men & women equally affected
- it is a disease of the elderly
- average age of presentation is 60 years
- rare in individuals < 30 years of age
Pathology
- complement fixing antibodies against parietal cell surface antigen(s)
- cellular immune response likely involved*
- atrophy of gastric mucosa (autoimmune atrophic gastritis)
- failure to secrete intrinsic factor
- inability to absorb vitamin B12
* pernicious anemia is unusually common in patients with agammaglobulinemia
Genetics
- relatives of patients with pernicious anemia have an increased incidence of the disease
Clinical manifestations
- primarily those of vitamin B12 deficiency
- scattered areas of skin hypopigmentation suggestive of vitiligo
- insidious in onset
- slowly progressing
Laboratory
- antiparietal cell autoantibodies (90%)*
- anti-intrinsic factor autoantibodies (60%)# (not indicated)[3]
- increased levels of serum gastrin
- complete blood count shows macrocytic anemia of vit B12 deficiency
- bone marrow biopsy shows megaloblastic changes of vit B12 deficiency
- pentagastrin stimulation test shows resistant achlorhydria
* antiparietal cell autoantibodies are found in 50% of individuals with gastric atrophy without pernicious anemia
# more specific than antiparietal cell autoantibodies; do not perform anti-intrinsic factor autoantibodies testing for diagnostic purposes[3]
Diagnostic procedures
- upper GI endoscopy
- surveillance for gastric carcinoma & gastric carcinoid tumors[6]
Complications
- gastric polyps & 2-fold risk of gastric cancer & carcinoid tumors
- associated with development of carcinoid, but predisposition to gastric adenocarcinoma controversial[7]
Differential diagnosis
Management
- lifelong parenteral vit B12 replacement
- surveillance for gastric cancer with fecal occult blood
- treatment with glucocorticoids may reverse the disease clinically & pathologically
More general terms
Additional terms
References
- ↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 655-56
- ↑ UpToDate 14.1 http://www.utdol.com
- ↑ 3.0 3.1 3.2 Medical Knowledge Self Assessment Program (MKSAP) 16, 18. American College of Physicians, Philadelphia 2012, 2018,
- ↑ Lahner E, Annibale B. Pernicious anemia: new insights from a gastroenterological point of view. World J Gastroenterol. 2009 Nov 7;15(41):5121-8. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/19891010
- ↑ NEJM Knowledge+ Gastroenterology
- ↑ 6.0 6.1 Rustgi SD, Bijlani P, Shah SC. Autoimmune gastritis, with or without pernicious anemia: epidemiology, risk factors, and clinical management. Therap Adv Gastroenterol. 2021;14:17562848211038771. PMID: https://www.ncbi.nlm.nih.gov/pubmed/34484423
- ↑ 7.0 7.1 Miceli E, Lenti MV, Gentile A et al. Long-term natural history of autoimmune gastritis: Results from a prospective monocentric series. Am J Gastroenterol 2024 May; 119:837 PMID: https://www.ncbi.nlm.nih.gov/pubmed/38050966 https://journals.lww.com/ajg/abstract/2024/05000/long_term_natural_history_of_autoimmune_gastritis_.17.aspx