Atrophic gastritis during long‐term omeprazole therapy affects serum vitamin B12 levels

Background : Omeprazole maintenance therapy for gastro‐oesophageal reflux disease (GERD) has been associated with an increased incidence of atrophic gastritis in H. pylori‐infected patients and with a decreased absorption of protein‐bound, but not of unbound cobalamin. Aim : To test the hypothesis that the combination of decreased cobalamin absorption and atrophic gastritis decreases serum cobalamin levels during omeprazole therapy. Methods : Forty‐nine H. pylori‐positive GERD patients were treated with omeprazole for a mean (± s.d.) period of 61 (25) months. At the start of omeprazole treatment (T0) and at the latest follow‐up visit (T1), serum was obtained for measurement of cobalamin. Corpus biopsy specimens were obtained at entry and follow‐up for histopathological scoring according to the updated Sydney classification. Results : At inclusion, none of the 49 patients had signs of atrophic gastritis. During follow‐up, 15 patients (33%) developed atrophic gastritis, nine of whom had moderate to severe atrophy. These 15 patients did not differ from the other 34 patients with respect to age, serum cobalamin at T0 or the duration of follow‐up. During follow‐up, no change was observed in the median serum cobalamin level in the 34 patients without atrophy; (T0) 312 (136–716) vs. (T1) 341 (136–839) pmol/L (P=0.1). In the 15 patients who developed atrophy, a decrease in cobalamin was seen from 340 (171 to 787) at baseline to 285 (156–716) at latest follow‐up (P