Atrophic gastrits 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; (T₁) 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 < 0.01). Conclusions: The development of atrophic gastritis during omeprazole treatment in H. pylori-positive GERD patients is associated with a decrease of serum vitamin B₁₂ levels.