Causes of Anaemia

Health encyclopaedia - Alphabetical Topic List

| A |

| B |

| C |

| D |

| E |

| F |

| G |

| H |

| I |

| J |

| K |

| L |

| M |

| N |

| O |

| P |

| Q |

| R |

| S |

| T |

| U |

| V |

| W |

| X |

| Y |

Each type of anemia has different causes:

Iron-deficiency anaemia is caused by a shortage of iron. It affects women much more often than men, because women lose some blood in each menstrual period between puberty and the menopause. An average healthy mixed diet will contain enough iron to make up normal menstrual losses, but unusually heavy periods, a poor diet, or large loses of weight can lead to a shortage of iron. In some cases there is also blood loss from elsewhere, especially from the stomach/ intestine. This may be from stomach and duodenal ulcers or from piles. Bleeding high up in the intestine turns the stools (faeces) black. Bleeding piles produce visible red blood. Chronic diseases, such as infections, cancer and rheumatoid arthritis, can cause iron-deficiency anaemia because the developing red cells in the bone marrow are unable to use the iron reserves.

Haemolytic anaemia occurs when red blood cell destruction is increased as the result of an acquired or inherited condition, which generally interferes with normal red blood cell production. They include hereditary Spherocytosis, Sickle cell anaemia, and Thalassaemia.

Megaloblastic anaemia develops if vitamin B12 or folic acid are lacking and is mainly caused by a diet low in fresh fruit and vegetables. Reduced absorption of folic acid may be due to excessive alcohol consumption and by some medicines. There is an increased need for folic acid during pregnancy. Folic acid deficiency also occurs in people with cancer and in those with coeliac disease.

Pernicious anaemia is caused by a shortage of vitamin B12. This is usually because the vitamin is not being absorbed, because the stomach lining does not produce a certain chemical (intrinsic factor). The bone marrow needs vitamin B12 in order to produce red blood cells. In pernicious anaemia the blood contains a smaller number of abnormally large cells (megablastic), which do not last as long as normal.

In Aplastic anaemia, the bone marrow does not make any new red cells, nor indeed any other kind of blood cells, and so the immune system canâ€™t work properly. The average life of a red cell is 120 days, so new cells have to be made all the time. If this does not happen, the anaemia will get steadily worse and create a very serious situation. About a third of all cases of aplastic anaemia follow virus infections, especially measles, mumps and hepatitis, or are caused by drugs such as butazolidine, sulphonamides, chloramphenicol by mouth or dipyrone. Because of this risk, most of these drugs are no longer prescribed. Inhaling benzene fumes can also cause aplastic anaemia. In most cases, however, the cause remains obscure. The condition is rare, affecting only 2 to 5 people per million.

Anaemia and pregnancy

Iron-deficiency anaemia and megaloblastic anaemia can occur during pregnancy.

A woman needs up to twice as much iron as usual during pregnancy (normally 30 mgs a day). Iron is needed to produce more blood to supply the baby with the necessary nutrients and oxygen. Up to half of all pregnant women require an iron supplement from the 20th week of pregnancy.

Lack of folic acid can make a pregnant woman anaemic. Folic acid is needed for the development of the babyâ€™s spinal cord and general growth. For most women, taking extra folic acid (400 micrograms daily) before conception (if possible) and during the first 12 weeks) pregnancy is recommended to avoid spinal damage to the baby.

Take the 5-a-day fruit and veg test