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What is anaemia? Anaemia Causes

What is anaemia?

Anaemia is the condition in which there is a reduction in the amount of the oxygen carrying molecule – hemoglobin – which is contained within red blood cells. This means that the anaemic person is not able to deliver as much oxygen to their body’s tissues 01 , 02 .

What causes anaemia?

The causes of anaemia can be broadly dived as being due to:

    • Decreased production of red blood cells/hemoglobin.
    • Increased loss or destruction of red blood cells.

Decreased production of red blood cells

The body requires several key nutrients from the diet in order to produce an adequate number of normal red blood cells and hemoglobin. These nutrients are iron, folic acid and vitamin B12.

symptoms of anaemia

Iron Deficiency Anaemia:

Iron deficiency is the most common cause of anaemia world-wide. Moreover, iron is necessary for the formation of haem – a component of the oxygen carrying molecule hemoglobin. The average adult has 3-5 grams of iron in their body, and 2/3 of this iron is present in hemoglobin.

The average daily requirement for iron is about 1milligram per day for an adult male. This requirement is higher in growing children, and menstruating women (about 1.5mg per day). Pregnant women may require up to 5-6mg per day in the late stages of pregnancy .

There are a number of reasons why a person may lack iron:

  • Not enough iron in the diet. The best source of iron is red meat (haem iron), and its absorption can be enhanced by vitamin C (contained in the juice of citrus fruit), and breast milk. Absorption is decreased by tannins (contained in tea).
  • Not absorbing the iron from the diet. (This can be due to disorders of the intestine, where iron is absorbed)
  • Increased iron demands – not met by increased intake. Iron demands increase in childhood (during growth spurts) and during pregnancy. During childhood, iron is essential for normal growth and development, especially of the brain.
  • Losing iron through blood loss. This is the most common cause of iron deficiency anaemia in adult males and post-menopausal females.

Vitamin B12 and Folic Acid Deficiency:

Vitamin B12 and folic acid are essential for normal DNA synthesis, and are therefore necessary for the production of new red blood cells. If these nutrients are lacking then there is a decreased production of new red blood cells, and formation of cells with abnormal shape and size because of problems making DNA.

Read more… B12 Deficiency and Low Iron 

Again there are a number of reasons why these nutrients may be lacking:

    • Not enough in the diet. Vitamin B12 is present in meat and milk, whilst folic acid is found in fresh green vegetables and fruit.
    • Not absorbed in the gut. This includes the condition known as pernicious anaemia. Here, the stomach fails to produce a key substance which is responsible for the absorption of vitamin B12 in the gut.
    • Vitamin B12 may be used up by bacteria in the gut before it is absorbed into the body.

Bone Marrow Abnormalities:

Red blood cells are made in the bone marrow, so problems with the marrow can also result in a decreased production of red blood cells. Usually there is also decreased production of other blood cells (like white blood cells). Bone marrow problems include bone marrow failure, leukaemia and invasion of the bone marrow by cancer


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Written by Dr. Ozair (CEO of SignSymptom.com) as physician writers are physicians who write creatively in fields outside their practice of medicine.

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