UNLABELLED: Fatigue in patients with gastrointestinal (GI) diseases can be caused by several conditions and anaemia is one of them. Anaemia can be caused by acute GI bleeding, or it can appear in relation to more chronic conditions: iron deficiency anaemia (IDA) and/or anaemia of chronic disease (ACD). Acute anaemia due to acute upper GI bleedings (AUGIB) is often treated with blood transfusions and/or oral iron supplementations. The need for blood transfusions prior to endoscopic intervention has been well described in guidelines. However, guidelines for the monitoring and treatment of anaemia in patients after nonvariceal AUGIB are generally lacking. A retrospective study showed that more than 80% of patients were discharged from hospital with anaemia and less than 20% of them were recommended iron supplementations. Chronic anaemia in inflammatory bowel diseases (IBD) is well known. Anaemia can be caused by deficiency conditions (iron, folic acid or vitamin B12); chronic bleeding; inflammation or medication (or a combination of these). Fatigue in IBD is found in 40% of IBD patients, even with disease in remission. The PhD dissertation is based on two studies. 1. A randomised placebo controlled trial where patients were allocated to iron supplementation (oral or intravenous) or placebo. Patients with nonvariceal AUGIB and anaemia were included in the study (N = 97). The primary follow-up time was 13 weeks, followed by additional three months follow-up. 2. A cross-sectional study including Scandinavian outpatients with IBD. Five hospitals in Denmark, Norway and Sweden included consecutively 5% of their cohort of patients with IBD (N = 429). The aims were: 1. To investigate the effect of iron supplementation in patients who had anaemia after endoscopic intervention for AUGIB. Furthermore, to investigate the health-related quality of life (HRQoL) and fatigue in these patients. 2. To determine the prevalence and type of anaemia, iron deficiency (ID) and fatigue in an unselected group of Scandinavian IBD outpatients. RESULTS: 1. Using haemoglobin (Hb) as a marker, the results of the intervention study on anaemic AUGIB patients showed that iron supplementations were superior to no treatment and intravenous iron was more effective to fill the patients iron stores than was oral iron. No differences in the Hb levels were found between the oral and intravenous iron groups after 13 weeks. Data on HRQoL and fatigue showed in general an improvement during the follow-up period. The improvement was not solely linked to treatment of anaemia. 2. The overall prevalence of anaemia in the Scandinavian population of IBD outpatients was 19%. Most patients had both IDA and ACD. The prevalence of ID was 35%. Fatigue was found in 44% of patients, and the physical dimensions of fatigue were the most marked. Anaemia and/or ID were not associated with increased fatigue. CONCLUSIONS: 1. Treatment with iron supplementations of post-discharge anaemia after AUGIB had significant effect on Hb levels. Intravenous iron supplementation should be chosen if adherence to treatment is essential. The patients' HRQoL was not affected by anaemia. 2. Anaemia in IBD outpatients was present in one of five patients and only 20% had pure IDA. The remains had pure "ACD" or a combination between ACD and IDA. Fatigue was present in nearly half of the patients and was not associated with anaemia, but was related to gender and age. Physical fatigue was the most affected dimension of fatigue.