Anaemias and other haematological changes due to disease of the alimentary tract.

Often anaemia and other haematological changes are unrelated to primary diseases of the erythron but are secondary to gastrointestinal alterations, such as occult or overt blood loss or defective absorption of essential haemopoietic factors. This overview emphasizes, through the description of different pathological conditions, the fundamental role of the gastrointestinal tract in maintaining a normal haematological balance. This role is jeopardized in diseases related to the liver and to the various sections of the alimentary tract from the oesophagus to the rectum. Of primary importance in inducing haematological changes which may be modified by curing the primary condition are essentially the diseases of the small intestine, following malabsorption of iron, folic acid and vitamin B12, such as conditions associated with small intestine bacterial overgrowth, tropical sprue, gluten sensitive enteropathy whipple's disease and various infections with intestinal parasites. Moreover, the Authors briefly survey the other pathological conditions of the alimentary tract often associated with chronic bleeding. In this context of particular relevance are the screening procedures which may reveal the presence of occult bleeding caused by neoplastic diseases. It is important that the clinician be aware of this possibility and of the underlying physiopathological mechanism of the diseases of the alimentary tract, so that appropriate and timely therapeutic measures may be undertaken.