Anaemia

Anaemia is not per se a symptom, people don’t usually go to the healthcare professional and declare that they have anaemia, rather they often present with symptoms which reflect anaemia, such as tiredness fatigue reduced exercise tolerance, shortness of breath on exertion or dizziness and feeling faint. These symptoms are manifestations of anaemia (amongst other things) which reflects a reduction in the oxygen carrying capacity of the blood. The majority of oxygen in the blood is carried by a molecule called haemoglobin which is manufactured within spefic cells within the bone marrow. Anaemia may be due to a lack of raw materials being absorbed, a failure to utilise those materials effectively (due to a primary bone marrow problem or a chronic disease which has secondary effects on the bone marrow) or due to blood loss, either through bleeding (often into the gut) or increased destruction (haemolysis).

There are numerous types of anaemia, some of which people are born with (thalassaemia or sickle cell anaemia), develop as a result of iron deficiency, often a result of poor intake, malabsorption or blood loss, classically this cause a microcytic anaemia. Anaemia may arise as a result of deficiency of  other vitamins or as a result of the failure of the bone marrow to function properly (often due to disease of the bone marrow rather than a gut problem). Sometimes anaemia may be a result of impaired absorption or utilisation of iron due to disease elsewhere in the body (either the kidneys or as a result of chronic inflammatory disease). Gastroenterologists are usually interested in iron deficiency anaemia where there is either poor absorption of iron due to gut disease or blood loss due to bleeding within the gut. In this case significant blood loss can occur without patients seeing blood in their stools. Iron deficiency due to excessive menstrual blood loss should usually be investigated by gynaecologists.

Causes of irondeficiency anaemia related to the gut include pancreatic insufficiency (maldigestion), coeliac disease, (malabsorption), bleeding gastric or duodenal ulcers, diverticular disease and colonic polyps or cancers.