Chapter 100. Megaloblastic Anemias (Part 8)

Table 100-4 Malabsorption of Cobalamin May Occur in the Following Conditions But Is Not Usually Sufficiently Severe and Prolonged to Cause Megaloblastic AnemiaGastric causesSimple atrophic gastritis (food cobalamin malabsorption)Zollinger–Ellison syndromeGastric bypass surgeryUse of proton pump inhibitorsIntestinal causesGluten-induced enteropathySevere pancreatitisHIV infectionRadiotherapyGraft-versus-host diseaseDeficiencies of cobalamin, folate, protein, ?riboflavin, ?nicotinic acidTherapy with colchicine, para-aminosalicylate, neomycin, slow-release potassium chloride, anticonvulsant drugs, metformin, phenformin, cytotoxic drugsAlcoholPernicious AnemiaPernicious anemia (PA) may be defined as a severe lack of IF due to gastric atrophy. ...
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Chapter 100. Megaloblastic Anemias (Part 8) Chapter 100. Megaloblastic Anemias (Part 8) Table 100-4 Malabsorption of Cobalamin May Occur in the FollowingConditions But Is Not Usually Sufficiently Severe and Prolonged to CauseMegaloblastic Anemia Gastric causes Simple atrophic gastritis (food cobalamin malabsorption) Zollinger–Ellison syndrome Gastric bypass surgery Use of proton pump inhibitorsIntestinal causes Gluten-induced enteropathy Severe pancreatitis HIV infection Radiotherapy Graft-versus-host diseaseDeficiencies of cobalamin, folate, protein, ?riboflavin, ?nicotinic acid Therapy with colchicine, para-aminosalicylate, neomycin, slow-releasepotassium chloride, anticonvulsant drugs, metformin, phenformin, cytotoxic drugs Alcohol Pernicious Anemia Pernicious anemia (PA) may be defined as a severe lack of IF due to gastricatrophy. It is a common disease in north Europeans but occurs in all countries andethnic groups. The overall incidence is about 120 per 100 000 population in theUnited Kingdom (UK). The ratio of incidence in men and women in Caucasians is~1:1.6 and the peak age of onset is 60 years, with only 10% of patients being premature graying or blue eyes, and in persons of blood group A. An associationwith human leukocyte antigen (HLA) 3 has been reported in some but not allseries and, in those with endocrine disease, with HLA-B8, -B12, and -BW15. Thelife expectancy is normal in women once regular treatment has begun. Men have aslightly subnormal life expectancy as a result of a higher incidence of carcinomaof the stomach than in control subjects. Gastric output of hydrochloric acid,pepsin, and IF are severely reduced. The serum gastrin level is raised, and serumpepsinogen I levels are low. Gastric Biopsy This usually shows atrophy of all layers of the body and fundus, with lossof glandular elements, an absence of parietal and chief cells and replacement bymucous cells, a mixed inflammatory cell infiltrate, and perhaps intestinalmetaplasia. The infiltrate of plasma cells and lymphocytes contains an excess ofCD4 cells. The antral mucosa is usually well preserved. Helicobacter pyloriinfection is infrequent in PA, but it has been suggested that H. pylori gastritisoccurs at an early phase of atrophic gastritis and presents in younger patients asiron deficiency anemia but in older patients as PA. H. pylori is suggested tostimulate an autoimmune process directed against parietal cells, the H. pyloriinfection then being gradually replaced, in some individuals, by an autoimmuneprocess.