[H. pylori infection and extra-digestive disease--idiopathic thrombocytopenic purpura and iron deficiency anemia--review].

Although H. pylori infection has been shown to be associated with a wide variety of non-gastrointestinal tract conditions, the studies are conflicting regarding these associations. In addition, a biological rationale for the proposed association with H. pylori infection is often lacking. Recent systematic reviews have shown a beneficial effect of H. pylori eradication in idiopathic thrombocytopenic purpura. The weighted mean complete response (platelet count > or = 100 x 10(9)/L) and overall response (platelet count > or = 30 x 10(9)/L and at least doubling of the basal count) were 42.7% (95% confidence interval[CI], 31.8%-53.9%) and 50.3% (95% CI, 41.6%-59.0%), respectively. These recent reviews demonstrated that diagnosis and treatment of H. pylori infection should be considered; however, randomized controlled clinical trials and immunological investigations on the mechanism are still lacking and are required. The results of meta-analysis indicated a significant association between H. pylori infection and iron deficiency or iron deficiency anemia, especially in high-risk groups. Although some case studies, small patient series and non-randomized trials have shown a beneficial effect of eradication in children with iron deficiency anemia, negative findings have also been reported. Further evaluation of the improvement of iron stores by eradication in large and well-controlled trials are required and would allow further additional studies to understand its biological mechanisms.