Patients developing inflammatory bowel disease have iron deficiency and lower plasma ferritin years before diagnosis: a nested case-control study

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Background Iron deficiency is common among inflammatory bowel disease (IBD) patients, generally reported without comparisons with controls. The aim of this study was to analyse if iron deficiency was more common among those later developing IBD compared to matched controls in a prospective setting. Methods We included 96 healthy subjects later developing IBD and 191 matched controls from the Northern Sweden Health and Disease Study. We analysed iron, ferritin, transferrin, and calculated transferrin saturation in plasma sampled at least 1 year prior to IBD diagnosis. Iron deficiency was defined as plasma ferritin 3 mg/L, iron deficiency could not be excluded if ferritin was