Immune thrombocytopenia (ITP) is a disorder that affects around 4 in 100,000 children every year. Its basis is a dramatic and often sudden reduction in the number of platelets in the blood (small blood cells that are important in stopping bleeding). It used to be called idiopathic thrombocytopenic purpura, which means that we don’t know what causes the low platelet count (idiopathic) and sometimes it causes big bruises (purpura).
Last updated August 2018 by Dr N Cooper, Consultant Haematologist, Hammersmith Hospital, Imperial Healthcare NHS Trust, London, UK.
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ITP is usually suspected because of the occurrence of abnormal bruising, small pin-point bleeds into the skin, and occasionally nosebleeds or other abnormal blood loss. It often follows a viral infection.
In ITP, platelets are removed by the body’s immune system as they are inappropriately regarded as ‘foreign’. ITP is thus a type of autoimmune disorder, meaning that the body is inappropriately attacking itself rather than foreign bodies, such as bacteria and viruses.
Mostly we do not know what triggers patients to get ITP. It may occur after infections such as measles, mumps, rubella or chicken pox. Research has also suggested an association between the measles, mumps and rubella (MMR) vaccination and ITP in young children although these episodes appear to be very rare and are mild and acute (short-lasting) with no children going on to develop serious permanent complications.
The diagnosis of ITP involves excluding other things that can cause a low platelet count. For example, some viruses, some drugs and some other haematology conditions can result in a low platelet count and bleeding.
In about 90 per cent of children, ITP is a trivial and rapidly self-correcting condition (acute ITP). The risk of serious bleeding in childhood ITP is very small and, usually, no treatment is necessary other than avoidance of aspirin or ibuprofen – these are part of a class of drugs called non-steroidal anti-inflammatory drugs (NSAIDs), which stop the platelets from working and further increase the risk of bleeding.
Treatment, if required, is aimed at suppressing the immune system to stop the inappropriate destruction of platelets, so reducing the risk of serious bleeding. This is usually achieved by either a short course of steroid drugs, which suppress the immune system, or injection of large amounts of intravenous immunoglobulin (a human, soluble antibody protein), which interfere with the destruction of platelets by the immune system.
In a few children, ITP runs a more prolonged course (chronic ITP). These children will usually be investigated further, including having a bone marrow test. They are also more likely to require treatment. A few children have persistent or chronic and troublesome ITP associated with bleeding. These patients should be referred to a haematology centre with experience in managing children with ITP.
There are a number of new treatments available for people who have persistent or chronic ITP:
- rituximab is a monoclonal antibody. It destroys B cells, which produce the antibodies that destroy the platelets. Good responses have been seen in children with ITP
- romiplostin and eltrombopag are licensed for use in adults and children with chronic ITP both in Europe and in the USA and have shown very good results, with an increase in the platelet count in most people, without many side effects. These drugs work in a different way, by stimulating the bone marrow to produce more platelets rather than suppressing the immune system. They need careful monitoring because the counts can fluctuate quite a lot. These should only be prescribed by a specialist centre where doctors have experience in how to use them.
- Immunosuppression with azathioprine or MMF can be used in patients not responsive to initial treatments
- Rarely children may need to have a splenectomy (this is where the platelets are destroyed). It is not common to take the spleen out for children with ITP now, because of other options. This should only be considered in a specialist centre.
The ITP Support Association
The ITP Support Association is a Registered Charity in England and Wales No. 1064480. It provides information and support to patients, families and health professionals affected by Immune Thrombocytopenia.
Group details last reviewed July 2018.