tailieunhanh - ANEMIAS AND OTHER RED CELL DISORDERS - PART 5

Các cơ sở của các hiệp hội chưa được biết. Thiếu máu ác tính phát sinh trong một phần đáng kể của bệnh nhân với loại hội chứng tuyến polyglandular tôi, một tình trạng tự miễn dịch với thất bại của nhiều tuyến nội tiết. Đáy và cơ thể của dạ dày là những khu vực chính của sự tham gia của bệnh thiếu máu ác tính. | 144 NUTRITION AND ANEMIA SECTION II The basis of these associations is unknown. Pernicious anemia also arises in a significant fraction of patients with polyglandular Glandular Syndrome Type I an autoimmune condition with failure of multiple endocrine glands. The fundus and body of the stomach are the primary regions of disease involvement with pernicious anemia. The loss of the parietal cells lowers acid secretion into the stomach in addition to reducing the production of intrinsic factor. These disturbances have multiple effects on cobalamin uptake. Gastric acidity promotes cobalamin separation from the structural components of food which is necessary to the ultimate formation of the complex between cobalamin and intrinsic factor. Gastric achlorhydria in pernicious anemia impairs this activity. Some of the cobalamin in food therefore passes through the gastrointestinal tract with no chance of uptake. The deficit of intrinsic factor is of course the major problem that impairs cobalamin absorption in people with pernicious anemia. Without this protein the receptors in the terminal ileum neither recognize cobalamin nor promote its uptake. The autoimmune process can also generate antibodies to intrinsic factor that directly block cobalamin binding to the protein. Secretion of these antibodies into the gastric juices further impairs vitamin uptake. These blocking antibodies against intrinsic factor also appear in the blood and are diagnostic of pernicious anemia. Hyperplasia of gastrin-producing cells also develops with pernicious anemia. High serum gastrin levels along with low serum levels of pepsinogen I and gastric achlorhydria are a frequent triad in pernicious anemia. Biopsy shows inflammation and gastric atrophy particularly in the fundus and body of the stomach. The portions of the cobalamin absorption mechanism beyond the stomach are normal in patients with pernicious anemia. The receptors in the terminal ileum that recognize the complex between .