Anemia, PerniciousIntrinsic FactorAchlorhydriaAnemiaSchilling TestVitamin B 12Anemia, MacrocyticVitamin B 12 DeficiencyCobalt IsotopesAnemia, MegaloblasticHydroxocobalaminGastrinsPostgastrectomy SyndromesParietal Cells, GastricAnemia, HypochromicGastric JuiceGastritis, AtrophicGastric MucosaFolic Acid DeficiencyGastritisAnemia, AplasticAnemia, HemolyticCarcinoid TumorEnterochromaffin CellsZollinger-Ellison SyndromeAutoimmune DiseasesCobalt RadioisotopesAutoantibodiesMalabsorption SyndromesEndocrine System DiseasesEthylaminesVitiligoStomachGastroscopyFanconi AnemiaAgammaglobulinemiaPolypsFolic AcidGastric FundusEdrophoniumH(+)-K(+)-Exchanging ATPaseAnemia, Hemolytic, Autoimmune