Updated 08 January 2018

What is anaemia?

Anaemia is a lack of red blood cells, resulting in a number of symptoms.


Anaemia is a condition in which your blood has a lower than normal number of red blood cells. This condition can also occur if your red blood cells don't contain enough haemoglobin (an iron-rich protein that gives blood its red colour). Haemoglobin helps red blood cells carry oxygen from the lungs to the rest of the body.

If you have anaemia, your body doesn't get enough oxygen-rich blood and, as a result, you may feel tired, weak and short of breath. With severe or long-lasting anaemia, the lack of oxygen in the blood can damage the heart, brain and other organs in the body. Very severe anaemia may even cause death.

Anaemia has three main causes: blood loss, lack of red blood cell production, or high rates of red blood cell destruction. These may be due to a number of diseases, conditions, or other factors.

  • Blood loss
    Blood loss is the most common cause of anaemia, especially iron-deficiency anaemia. Heavy menstrual periods or bleeding in the digestive or urinary tract can cause blood loss. Surgery, trauma, or cancer can also lead to blood loss.
  • Lack of red blood cell production
    Both acquired and inherited conditions and factors can prevent your body from making enough red blood cells. Examples of acquired conditions and factors that can cause this include diet, hormones, some chronic diseases and pregnancy. Aplastic anaemia can also prevent your body from making enough red blood cells – this condition can be acquired or inherited.

    A diet that lacks iron, folic acid, or vitamin B12, or conditions that make it hard for your body to absorb nutrients, can also prevent your body from making enough red blood cells.

    Your body needs the hormone erythropoietin to make red blood cells and a low level of this hormone may cause anaemia.

    Chronic diseases, like kidney disease and cancer, can make it hard for the body to make enough red blood cells, and those with HIV/Aids can develop anaemia due to infections or medicines used to treat the disease.

    Anaemia can occur during pregnancy due to low levels of iron and folic acid and changes in the blood.
  • High rates of red blood cell destruction
    There are various conditions that can cause your body to destroy too many red blood cells such as an enlarged spleen, sickle cell anaemia, thalassaemia and a lack of certain enzymes.

Anaemia is a common condition. It occurs across all age, racial and ethnic groups. Both men and women can have anaemia, but women of childbearing age are at higher risk for the condition as they lose blood from menstruation. Anaemia can also develop during pregnancy due to low levels of iron and folic acid and changes in the blood.Infants younger than two years are also at risk for anaemia because they may not get enough iron in their diet.

Reviewed by Drs Natasha Sewpersad and Yasmin Goga, Inkosi Albert Luthuli Central Hospital, and Sunil Soni, Chairperson: South African Thalassaemia Association, June 2010


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