Idiopathic thrombocytopenic purpura (ITP) is an autoimmune
disease affecting platelets. Many people have no symptoms. If symptoms
occur they can range from mild bruising to severe bleeding. In children
the condition usually goes away in 6-8 weeks, without any treatment. In
adults it is usually a lifelong condition. Treatment may or may not be
necessary and may include steroids, immunoglobulin and surgery.
Understanding platelets
Platelets are tiny components of the blood which help blood to clot
when we injure ourselves. They are also known as thrombocytes. They are
made inside bone, in the bone marrow. They are released into the
bloodstream and travel through the body for about seven days, before
they are removed by the spleen. The spleen is an organ that lies at the
top of the abdomen under the ribs on the left-hand side.
A normal number of platelets is between 150 and 400 x 10
9
per litre. This is found by a blood test. If you have too many
platelets, your blood will clot too easily. If you do not have enough
platelets, you may bruise and bleed more easily than usual.
What is idiopathic thrombocytopenic purpura?
Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease
involving platelets. In autoimmune disorders your body makes an antibody
that damages another part of your body. In ITP the antibodies are made
against platelets. Once the antibodies have attached to platelets, the
platelets do not work so well. They are also removed more quickly by the
spleen because they are abnormal.
- Idiopathic means that there is no known underlying cause found.
- Thrombocytopenic means not enough platelets.
- Purpura is a purple-red rash.
IDIOPATHIC THROMBOCYTOPENIC PURPURA IN CHILDREN
How common is it in children?
ITP occurs in about 5 in 100,000 children. Girls are three times more likely to have it than boys.
What are the symptoms?
- Most children will not have any symptoms.
- Those who do develop symptoms have bruising and the rash - purpura.
Some have bleeding such as nosebleeds. It usually appears over 1-2 days.
The condition often occurs about 2-3 weeks after an infection (often a
common viral infection). Occasionally, it follows immunisation. The
symptoms disappear over 6-8 weeks in most cases.
- Very occasionally, it causes severe bleeding which requires emergency treatment.
- The platelet levels in about 1 in 10 affected children do not ever
return to normal, which means that they have developed chronic
(persistent) ITP.
So, what seems to happen in children with ITP is that the immune
system is triggered to produce antibodies against the platelets by an
infecting virus or other germ. In most cases, this is a temporary immune
reaction that lasts several weeks only, and then symptoms go. But, in a
few cases, the immune system continues to be faulty and the condition
becomes long-standing.
How is it diagnosed?
ITP is diagnosed by a blood test called a full blood count. This test
shows that there are fewer platelets than normal. The laboratory will
also have a look at the blood under a microscope.
Sometimes
different tests will be needed to make sure that the low number of
platelets is not due to another of the potential causes. Rarely, this
involves taking a sample of bone marrow.
What is the treatment?
Most children will not need treatment, even if the number of
platelets is very low. The decision to treat is usually based on whether
your child has serious bleeding or very pronounced bruising and
purpura. If the symptoms are mild, usually there will be no need for
treatment. Your child will need to have the full blood count repeated on
a few occasions to check that the platelet numbers are stable and that
the rest of the blood cell counts are remaining normal. If your child
has bleeding and more severe bruising or purpura, treatment may be
considered. The aim of treatment is to improve symptoms and increase the
number of platelets.
If treatment is needed then the decision
on what treatment to use can be difficult. This is because there have
not been many studies testing the treatments against each other. The
options for treatment include:
- Prednisolone. This is often the first type of
treatment tried. It is a steroid medication and is taken as syrup or
tablets. This may be given as a high dose over a short period of time
(four days) or as a lower dose for a longer time (two weeks).
Prednisolone has been shown to increase the number of platelets quickly
in about 3 in 4 children with ITP.
- Other steroid options. High-dose methylprednisolone
or high-dose dexamethasone. These are other types of steroid medicines
that have also been shown to be effective in differing degrees.
Dexamethasone is not often used in children.
- Intravenous immunoglobulin (IVIg). This is an
injection of a protein into the bloodstream and has been shown to work
well in about 8 in 10 children in increasing the number of platelets. It
is not usually used as the first option because it involves an
injection. It can also cause quite a lot of side-effects and is quite
expensive. It may be used as an emergency treatment if your child has
severe bleeding or needs surgery.
- Anti-D immunoglobulin. This is another type of
protein that is also effective and causes fewer side-effects than IVIg.
It can only be given to children whose blood group is RhD positive.
- Platelet transfusions. In a life threatening
situation your child may be given a transfusion of platelets at the same
time as being treated with steroids and IVIg. This only helps to
increase the number of platelets for a short time. The transfused
platelets are also attacked by the antibody that the body has produced
and are destroyed by the spleen.
- Other medicines. A number of other medicines are
being trialled. These are not routinely recommended, as not enough
information is known yet about their use and side-effects.
- Surgery to remove the spleen (splenectomy). This is
very rarely done in children with ITP. It is only really considered as
an option if your child has life- threatening bleeding or severe chronic
disease that is affecting their day-to-day functioning.
In chronic ITP, usually no treatment is needed but your child will
need to have regular blood tests and specialist review. If they have an
injury or are involved in an accident you will be advised to take them
to your local hospital emergency department for review. If the disease
is severe, then the treatments outlined above may be considered.
