Chapter 100. Megaloblastic Anemias (Part 8)

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Table 100-4 Malabsorption of Cobalamin May Occur in the Following Conditions But Is Not Usually Sufficiently Severe and Prolonged to Cause Megaloblastic Anemia Gastric causes Simple atrophic gastritis (food cobalamin malabsorption) Zollinger–Ellison syndrome Gastric bypass surgery Use of proton pump inhibitors Intestinal causes Gluten-induced enteropathy Severe pancreatitis HIV infection Radiotherapy Graft-versus-host disease Deficiencies of cobalamin, folate, protein, ?riboflavin, ?nicotinic acid Therapy with colchicine, para-aminosalicylate, neomycin, slow-release potassium chloride, anticonvulsant drugs, metformin, phenformin, cytotoxic drugs Alcohol Pernicious Anemia Pernicious 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) Table 100-4 Malabsorption of Cobalamin May Occur in the Following Conditions But Is Not Usually Sufficiently Severe and Prolonged to Cause Megaloblastic Anemia Gastric causes Simple atrophic gastritis (food cobalamin malabsorption)
Zollinger–Ellison syndrome Gastric bypass surgery Use of proton pump inhibitors Intestinal causes Gluten-induced enteropathy Severe pancreatitis HIV infection Radiotherapy Graft-versus-host disease Deficiencies of cobalamin, folate, protein, ?riboflavin, ?nicotinic acid
Therapy with colchicine, para-aminosalicylate, neomycin, slow-release potassium chloride, anticonvulsant drugs, metformin, phenformin, cytotoxic drugs Alcohol Pernicious Anemia Pernicious anemia (PA) may be defined as a severe lack of IF due to gastric atrophy. It is a common disease in north Europeans but occurs in all countries and ethnic groups. The overall incidence is about 120 per 100 000 population in the United 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 association with human leukocyte antigen (HLA) 3 has been reported in some but not all series and, in those with endocrine disease, with HLA-B8, -B12, and -BW15. The life expectancy is normal in women once regular treatment has begun. Men have a slightly subnormal life expectancy as a result of a higher incidence of carcinoma of the stomach than in control subjects. Gastric output of hydrochloric acid, pepsin, and IF are severely reduced. The serum gastrin level is raised, and serum pepsinogen I levels are low. Gastric Biopsy This usually shows atrophy of all layers of the body and fundus, with loss of glandular elements, an absence of parietal and chief cells and replacement by mucous cells, a mixed inflammatory cell infiltrate, and perhaps intestinal metaplasia. The infiltrate of plasma cells and lymphocytes contains an excess of CD4 cells. The antral mucosa is usually well preserved. Helicobacter pylori infection is infrequent in PA, but it has been suggested that H. pylori gastritis occurs at an early phase of atrophic gastritis and presents in younger patients as iron deficiency anemia but in older patients as PA. H. pylori is suggested to stimulate an autoimmune process directed against parietal cells, the H. pylori
infection then being gradually replaced, in some individuals, by an autoimmune process.