Anemia, PerniciousGastritisIntrinsic FactorAchlorhydriaGastritis, AtrophicAnemiaSchilling TestVitamin B 12Anemia, MacrocyticIntestinal AbsorptionGastric MucosaVitamin B 12 DeficiencyAbsorptionCobalt IsotopesGastrinsAnemia, MegaloblasticParietal Cells, GastricPostgastrectomy SyndromesHydroxocobalaminGastric JuiceAnemia, HypochromicStomachHelicobacter pyloriGastroscopyHelicobacter InfectionsStomach NeoplasmsAutoimmune DiseasesCarcinoid TumorAnemia, AplasticMalabsorption SyndromesEnterochromaffin CellsZollinger-Ellison SyndromeAutoantibodiesAnemia, HemolyticFolic Acid DeficiencyCobalt RadioisotopesGastric FundusH(+)-K(+)-Exchanging ATPaseDuodenal UlcerPolypsEndocrine System DiseasesEthylaminesVitiligoPyloric AntrumFanconi AnemiaGastric AcidAgammaglobulinemiaGastritis, HypertrophicEdrophoniumFolic Acid