Complications
Loss of intrinsic factor as a result of atrophic gastritis, antiparietal cell antibodies, and/or anti-intrinsic factor antibodies results in malabsorption of dietary cobalamin.[24][30][31][35][36][37][38][78][79] Cobalamin deficiency, which takes many years to develop because of large body stores, can be tracked by monitoring the blood count as well as serum cobalamin levels. Measurement of the serum concentration of methylmalonic acid, a metabolic intermediary, may be more sensitive for the diagnosis than serum vitamin levels. Methylmalonic acid is elevated in cobalamin deficiency due to decreased rate of metabolism. Parenteral cobalamin prevents and treats the deficiency.
Several epidemiologic studies have suggested an association between proton-pump inhibitor use and increased risk of osteoporosis-related hip fracture.[17][18][19]
However, one large randomized controlled trial reported no statistically significant difference in fracture risk between pantoprazole and placebo groups over a 3-year period.[16]
High levels of gastrin, acting via CCK-2 receptors on gastric enterochromaffin-like (ECL) cells, induce these cells to become hyperplastic and some, over many years, to become dysplastic and transform into carcinoid tumors.[1][66]
Between 70% and 80% of gastric carcinoid tumors arise in patients with atrophic gastritis, particularly in those with pernicious anemia. It is thought that ECL cells, under stimulation of gastrin, evolve through hyperplasia, dysplasia, and eventually neoplasia. These carcinoid tumors are typically small, polypoid, multicentric, and well differentiated.[66] Although generally asymptomatic, gastric carcinoids may rarely present with abdominal pain and bleeding.
Acid facilitates the absorption of dietary iron by liberating heme iron from its apoprotein and converting nonheme iron, which is largely in the form of ferric hydroxide (Fe3+), to the more easily absorbed ferrous (Fe2+) form.[68][69] Iron-deficiency anemia can be tracked by monitoring the blood count as well as serum iron levels. Administering oral iron in combination with ascorbic acid (vitamin C) can prevent as well as treat this complication.
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