Low B-12 levels in chronic idiopathic urticaria

Recent studies suggest that autoimmune mechanisms may be involved in the etiology of chronic idiopathic urticaria (CIU). There is a higher prevalence of B-12 deficiency in autoimmune diseases and possibly in gastric Helicobacter pylori (H. pylori) infection. The frequency of B-12 deficiency in CIU is unknown. Our objective in this study was to determine the prevalence of B-12 deficiency in patients with CIU and also its relationship to gastric H. pylori infection and serologic markers of autoimmunity in these groups. Thirty-three patients with CIU and 27 healthy controls were included in the study. Serum vitamin B-12 levels, H. pylori infection and serological markers of autoimmunity (anti-thyroglobulin, thyroid microsomal, gastric parietal cell and antinuclear autoantibodies) were investigated. H. pylori infection was determined according to serology and gastric biopsy in 19 patients, serology and urea breath test in 4 patients and serology alone in the remaining 10 patients. Serum B-12 levels were below the normal reference range in 11 /33 (33.3%) patients with CIU. The mean serum B-12 levels among patients with CIU and the controls were 281+/-127.5 pg/ml and 465.1+/-140.3 pg/ml (p=0.0001), respectively. Anti-thyroid antibodies were positive in 6 of 11 patients (54.5%) with low B, levels, but only in 4 of 27 (14.8%) healthy controls (p=0.019). Anti-GPC antibodies were positive in 4 of 11 (36.4%) patients with CIU and low B, levels, but only in 2 of 27 (7.4%) healthy controls (p=0.047). In CIU patients, there was no difference in the frequency of IgG H. pylori antibodies between those with low B-12 levels and normal B-12 levels. Among the 19 patients who had been performed gastric endoscopy, 15 patients (78.9%) had chronic antral gastritis, 2 patients (10.5%) had atrophic gastritis and there were normal findings in 2 patients (10.5%). In conclusion, serum B-12 levels were found to be below the normal reference range in 33% of the patients with CIU. An association between low B-12 levels and H. pylori could not be shown. The higher frequency of antithyroid and anti-GPC antibodies in patients with low B-12 levels suggest that low B-12 levels in CIU may be autoimmune in nature.