Aplastic Anaemia

Aplastic anaemia (AA) is a rare condition in which the bone marrow fails to produce all three major types of blood cell. It is not a form of cancer.

Video: Sarah’s Aplastic Anaemia story

Types of aplastic anaemia

There are several types of aplastic anaemia:

  1. Acquired aplastic anaemia – this is the most common type where there is often no obvious or known cause.
  2. Inherited bone marrow failure syndromes – there are rare inherited conditions which may lead patients on to develop aplastic anaemia. The most common of these is Fanconi anaemia.

How common is Aplastic Anaemia?

Aplastic anaemia only affects about 120 – 150 people each year in the UK.

Although it can affect anyone, at any age, it is most common between 10 and 20 years old and in people aged over 60 – 65 years old.

What causes Aplastic Anaemia?

It is generally accepted that, in most cases, acquired AA is caused by the body’s immune system damaging stem cells in the bone marrow. When the immune system attacked the body’s own cells, this is called an autoimmune disease.

In about three-quarters of all cases there is no obvious underlying reason why the immune system is damaging stem cells. This is called idiopathic aplastic anaemia.

In the remaining quarter, there may have been recent exposure which is thought to have triggered the development of AA:

Medicine – one example of a medicine that may cause AA is the antibiotic chloramphenicol, when given orally or by injection. This drug is only used for life-threatening infections which are resistant to other antibiotics.

Chemical – one example is the exposure to high levels of benzene. In the UK, this probably accounts for very few cases, as there are strict limits on exposure to this sort of chemical.

Viral infection – about 1 in 10 patients with AA have had a recent viral infection, often hepatitis. In these cases, the AA may develop because the patient’s stem cells have some surface proteins which are similar to those on the virus. The immune system becomes ‘confused’ and produces antibodies which are targeted at the virus but also damage blood-forming stem cells.

Symptoms of Aplastic Anaemia

The symptoms of AA are not caused by damage to stem cells but by the lack of normal blood cells. The most common symptoms are those of anaemia or of bleeding due to low platelet counts but infection may also be a symptom at diagnosis, especially if the neutrophil count is very low.

Anaemia due to lack of red blood cells – weakness, tiredness, shortness of breath, light-headedness, palpitations.

Bleeding and bruising due to lack of platelets – purpura (small bruises in the skin), nosebleeds, bleeding gums, vision problems (bleeding in the retina). Severe bleeding is not common but requires urgent treatment.

Infections due to lack of white blood cells – infection may be a significant problem at the time of diagnosis. Severe infection requires urgent treatment.


How does AA affect your body?

AA is the reduced production of blood cells, although, those that are produced are normal, work normally and have a normal life span in the blood.

An important feature of AA is that the marrow is hypocellular, which means that it contains very few blood-forming cells compared with a normal marrow. There may be “pockets” od normal marrow cells left, which means that a single normal marrow sample mat nor always be enough to make a diagnosis of AA.

Classification of AA

The classification is based on how low the numbers of blood cells have fallen, which can be found out by a blood count.

To make a diagnosis of AA, at least two of the following must be present:

  • Haemoglobin less than 100g/L
  • Platelet count less than 50 x 109/L
  • Neutrophil count less than 1.5 x 109/L

AA is classified as non-severe, severe or very severe.

Non-severe aplastic anaemia

This meets the above criteria for aplastic anaemia but does not meet the criteria for severe or very severe aplastic anaemia.

Severe aplastic anaemia

Hypocellular bone marrow and any two of the following:

  • A low platelet count (less than 20 x 109/L)
  • A reticulocyte count less than 20 or 60 x 109/L
  • A neutrophil count less than 0.5 x 109/L

Very severe aplastic anaemia

Hypocellular bone marrow and any two of the following:

  • A low platelet count (less than 20 x 109/L)
  • A reticulocyte count less than 20 or 60 x 109/L
  • A neutrophil count less than 0.2 x 109/L

The difference between severe and very severe AA is how low the number of neutrophils falls; which increases the risk of severe infection.

Hypocellular bone marrow is defined as bone marrow cells <25%, or 25-50% with less than 30% of stem cells in your bone marrow.

Treating AA

The aim of treatment is to restore blood cell production.

Non-severe AA sometimes clears up without treatment (spontaneous recovery) but this is not common. Some patients with non-severe AA may not require treatment initially if they don’t need transfusions – often referred to as ‘watch and wait’ or active monitoring. If spontaneous recovery has not happened by the time all tests have been done and treatment plans discussed, it is unlikely to happen and it is normal to start treatment is you are needing blood and/or platelet transfusions.

All patients with severe or very severe AA are likely to need blood and platelet transfusions and treatment to prevent/control infections. This is called supportive care.

Supportive care

There are three elements to supportive care:

  • Treatment of anaemia – there are no options available to prevent anaemia but it can be treated with transfusions. Sometimes a large number of red cell transfusions can create a build-up of iron in the body, but this can be treated with drugs.
  • Prevention and treatment of infection – if the neutrophil count is below normal, antibodies and antifungal drugs may be given to reduce the risk of infection. If you develop fever or any other symptoms which may indicate an infection, it is important to let your doctor or specialist nurse know immediately.
  • Prevention of bleeding – Low platelet levels can make bleeding a problem. Regular transfusions can be given if the count falls below 10 x 109/L (or 20 x 109/L in the presence of fever and/or infection).

Definitive treatment

Definitive treatment aims to either control damage to bone narrow stem cells (immunosuppression) or replacing damaged stem cells with healthy cells from a donor (stem cell transplant). The choice of treatment is based on the severity of AA as well as the age and general health of the patients and the availability of a bone marrow donor.


This treatment involves the use of the drugs to control the activity of the immune system and reduce the damage being done to bone marrow stem cells. This is the preferred treatment for patients with non-severe AA and for patients with severe or very severe AA who are over 35-50 years old or not able to have a stem cell transplant.

The most widely used combination is an antibody called anti-thymocyte globulin (ATG) combined with a drug called ciclosporin (CSA). This is successful in around 70% (two thirds) of patients.

If you have received immunosuppressive treatment, you should not have any vaccinations, including the annual flu vaccination This is because there is a theoretical risk that vaccinations might cause your AA to return.

If you need a transfusion during or after immunosuppression treatment, it is important that you should be given irradiated blood cells. This will protect against a possible reaction called transfusion-related graft vs host disease (GVHD is a rare complication that develops 4 – 30 days after a blood transfusion).

Stem Cell transplant

For younger/fitter patients who have a fully-matched sibling, a donor stem cell transplant is the first treatment of choice. This involves doses of chemotherapy and an antibody to suppress the body’s immune cells so that they don’t reject the new stem cells followed by a transplant of healthy stem cells from the donor. The treatment is reported as offering a 75% – 90% chance of long term cure.

If you have received a stem cell transplant, you should receive all your recommended vaccinations as normal.

If you need a transfusion after a stem cell transplant, it is important that you should be given irradiated blood cells. This will protect against transfusion-related GVHD.

Further information

We have free patient information available for AA patients.

You can download the booklets on our information pages here.

Alternatively, you can have the information delivered free of charge by requesting it through our resources page. 

Patient stories

Sarah Cheeseman was diagnosed with aplastic anaemia in 2007, read her story here.

Further support for AA

The Aplastic Anaemia Trust is the only charity in the UK dedicated solely to research into aplastic anaemia and allied rare bone marrow failures. They also provide practical information and advice to patients and their families as well as peer-to-peer support.

For further information on the latest research and to access information and support, please contact The AAT via their website www.theaat.org.uk