What is aplastic anaemia?
Aplastic anaemia is a rare disorder in which the bone marrow fails to produce enough blood cells. This happens because the normal blood forming cells (stem cells) are replaced by abnormal fat cells.
Although aplastic anaemia is not a malignant disease (cancer) it can be very serious, especially if the bone marrow is severely affected and there are very few blood cells left in circulation. Without adequate numbers of blood cells people with aplastic anaemia can become anaemic (low red blood cells) and more susceptible to infections (low white blood cells), and to bleeding and bruising more easily (low platelets).
The term aplastic anaemia is usually understood to refer to the acquired disorder which is a non-malignant bone marrow disease. There are other conditions that are congenital (present at birth), inherited (e.g. Fanconi Anaemia) or a form of aplastic anaemia that may develop over a person’s life as a result of treatment (like chemotherapy) for malignant diseases. These conditions need to be ruled out before a diagnosis of acquired aplastic anaemia can be made.
Fanconi anaemia can be diagnosed and distinguished from acquired aplastic anaemia by a blood test. Fanconi anaemia affects brothers and sisters within a family. Children with Fanconi anaemia are short and have abnormalities of the forearms or hands and a gradual but progressive failure of the bone marrow. The anaemia usually develops in childhood but may present later in life as adolescent or adult.
There is common thought that acquired aplastic anaemia results when the bone marrow stem cells are damaged by an auto-immune reaction in the body. An auto-immune reaction can result from no specific trigger or underlying cause. The body’s own immune system attacks its own cells in an auto-immune reaction. Some types of aplastic anaemia may have an identifiable trigger that caused the auto-immune response.
How common is aplastic anaemia?
There is no consensus on the incidence of aplastic anaemia in Australia. Worldwide figures suggest the incidence of aplastic anaemia is 0.7-4.1 cases per million people.
Who gets aplastic anaemia?
Aplastic anaemia is more commonly diagnosed in patients aged between 10 and 20, and over 40. There is a slight increased incidence in men compared to women.
What causes aplastic anaemia?
In the majority of cases aplastic anaemia is an acquired disorder that develops at some stage in the person’s life. This means that it is usually not inherited (passed down from parent to child), and it is not present at birth. Several potential triggers for the development of aplastic anaemia have been identified and these include:
- exposure to certain drugs – these include certain drugs to treat arthritis or an over active thyroid, some drugs used in psychiatry and a few antibiotics. The risk of aplastic anaemia resulting from taking these drugs is very small.
- exposure to certain chemicals – there is a long list of chemicals which have been suspected of causing aplastic anaemia. The link between these chemicals and the incidence of aplastic anaemia is often very weak.
- viruses – some patients diagnosed with aplastic anaemia have suffered a virus in the weeks prior to their diagnosis
- radiation exposure.
However, in many cases of aplastic anaemia the cause remains unknown and with children it is often impossible to prove what caused the aplastic anaemia.
What are the symptoms of aplastic anaemia?
The main symptoms of aplastic anaemia are caused by a lack of normal blood cells. Common symptoms include:
- anaemia due to a lack of red cells, causing persistent tiredness, dizziness, paleness, or shortness of breath when physically active
- frequent or repeated infections and slow healing, due to a lack of normal white cells, especially neutrophils
- increased or unexplained bleeding or bruising, due to a very low platelet count.
Occasionally people have no symptoms at all and aplastic anaemia is diagnosed during a routine blood test. Some of these symptoms described may also be seen in other illnesses, including viral infections, so it is important to see your doctor so that you can be examined and treated properly.