Malabsorption of vitamin B12 in dermatitis herpetiformis and its association with pernicious anaemia.

Serum vitamin B12 concentrations were determined in 129 patients and a pentagastrin test performed in 116 patients with dermatitis herpetiformis (DH). Low serum vitamin B12 levels were found in 27 patients (21%) and achlorhydria in 30. Forty-two patients with achlorhydria and/or vitamin B12 deficiency were subjected to further haematological and gastrointestinal investigations. Functional or morphological involvement of the small intestine was seen in almost all patients with vitamin B12 deficiency but, in addition, atrophic gastritis resulting in defective secretion of intrinsic factor (pernicious anaemia) was found in 8 cases (7% of all DH patients). Thus, a low vitamin B12 level in DH patients should result in a careful gastrointestinal examination as both an atrophic gastritis and a coeliac-like enteropathy have further clinical implications.