Anemia, PerniciousIntrinsic FactorAchlorhydriaAnemiaSchilling TestVitamin B 12Anemia, MacrocyticVitamin B 12 DeficiencyCobalt IsotopesAnemia, MegaloblasticHydroxocobalaminGastrinsPostgastrectomy SyndromesParietal Cells, GastricGastric JuiceAnemia, HypochromicGastritis, AtrophicGastric MucosaGastritisAnemia, AplasticCarcinoid TumorEnterochromaffin CellsZollinger-Ellison SyndromeAnemia, HemolyticFolic Acid DeficiencyAutoantibodiesAutoimmune DiseasesCobalt RadioisotopesEndocrine System DiseasesMalabsorption SyndromesEthylaminesVitiligoGastroscopyStomachPolypsFanconi AnemiaAgammaglobulinemiaGastric FundusEdrophoniumFolic AcidAnemia, Hemolytic, AutoimmuneH(+)-K(+)-Exchanging ATPaseStomach Neoplasms