Anaemia in gastroenterology

Anaemia related to the digestive system is mostly secondary to dietary deficiency, malabsorption, or chronic bleeding. We review the World Health Organization definition of anaemia and its morphological classification (microcytic, macrocytic and normocytic). We detail the importance of iron, vitamin B12 and folate deficiency anaemia; the interpretation of laboratory tests to differentiate between the causes of anaemia, especially anaemia of chronic disease; and the management options for patients with anaemia caused by gastrointestinal disease.