Selective vitamin B12 malabsorption in adult coeliac disease. Report on three cases with associated autoimmune diseases.

Three cases of adult coeliac disease with severe vitamin B12 deficiency not accompanied by folate or iron depletion are presented. Two of the patients had the extremely rare combination of coeliac disease and lack of intrinsic factor and autoimmune thrombocytopenic purpura. A close association between coeliac disease and autoimmunity is indicated by the development of autoimmune thyroiditis in the third patient. Vitamin B12 malabsorption caused by coeliac disease is emphasized as a pathogenetic mechanism of megaloblastic anaemia.