Anemia, PerniciousGastritisIntrinsic FactorAchlorhydriaGastritis, AtrophicAnemiaSchilling TestVitamin B 12Anemia, MacrocyticGastric MucosaVitamin B 12 DeficiencyCobalt IsotopesGastrinsAnemia, MegaloblasticParietal Cells, GastricPostgastrectomy SyndromesHydroxocobalaminGastric JuiceAnemia, HypochromicHelicobacter pyloriStomachGastroscopyHelicobacter InfectionsStomach NeoplasmsAutoimmune DiseasesCarcinoid TumorAnemia, AplasticEnterochromaffin CellsAutoantibodiesZollinger-Ellison SyndromeAnemia, HemolyticFolic Acid DeficiencyMalabsorption SyndromesGastric FundusCobalt RadioisotopesDuodenal UlcerPolypsH(+)-K(+)-Exchanging ATPaseEndocrine System DiseasesEthylaminesVitiligoPyloric AntrumFanconi AnemiaAgammaglobulinemiaGastric AcidGastritis, HypertrophicEdrophoniumFolic AcidAnemia, Hemolytic, Autoimmune