A review of the literature reveals that very few studies have assessed the potential co-existence of vitamin B12 deficiency due to gastric parietal cell autoantibodies. While Segal et al. in 2004 published a study which found that 49% of patients with RA had vitamin B12 deficiency, no assessment of the etiology or the presence of autoantibodies was made. While Goeldner et al. in 2011 and Datta et al. in 1990 demonstrated that anti-gastric parietal cell antibodies (anti-GPC Ab) were found in <5% to 28% of RA patients respectively, no additional testing was implemented to determine the significance, specifically whether or not the presence of anti-GPC Ab related to vitamin B12 deficiency.