Hematological Extradigestive Manifestations of Helicobacter pylori Infection in Childhood

Helicobacter pylori infects more than 50% of the world population and is acquired in infan‐ cy. Higher prevalence is found in developing countries, and within geographic areas the predominance correlates inversely with socioeconomic status, especially with living con‐ ditions during childhood. Initially, in adults, H. pylori was only associated with gastric diseases, such as peptic ulcer, gastritis, gastric adenocarcinoma, and gastric mucosa-asso‐ ciated lymphoid tissue (MALT) lymphoma, and in childhood, with chronic gastritis and duodenal ulcers in children. Recently, H. pylori has been related to non-gastric diseases, including hematological disorders such as iron deficiency anemia (IDA), chronic idio‐ pathic thrombocytopenia (cITP), and vitamin B12 deficiency. H. pylori can trigger autoim‐ mune atrophic gastritis and be responsible initially for an oral iron refractory anemia. Other hematological associations have been made, such as an increased risk of childhood leukemia in children of H. pylori-infected mothers and gastric bleeding in children with coagulation pathologies. H. pylori infection is important in the immune pathogenesis of chronic gastric inflammation and hematological diseases. The diagnostic methodology is based on non-invasive (serology, C-urea breath test, stool HP antigen) and invasive tests. The scientific community discussed and incorporated in international consensus for the investigation and management of these hematological extragastric pathologies (IDA, cITP, vitamin B12 deficiency, and MALT lymphoma). In children, a similar attitude was obtained in all of these pathologies except for cITP, in which the investigation for H. pylo‐ ri is not indicated.