Idiopathic thrombocytopenic purpura (ITP)

Prolonged use of steroids is also associated with osteoporosis.

Acute ITP often responds to a three to four week course of steroids, after which treatment is stopped.

In chronic ITP there may be an initial improvement, but the platelet count falls again once the dose is reduced or withdrawn. If this happens, you may need an alternative treatment or a long-term low dose steroid plus measures to protect against osteoporosis, for example medicines and monitoring of bone density.

Immunoglobulin

Immunoglobulins are antibodies that are made by the immune system following exposure to a foreign protein, for example a virus.

If the foreign protein appears again in the body at a later date, it is 'recognised' by the antibody which then activates the rest of the immune system.

It can take the body days or weeks to make immunoglobulins in response to a foreign protein, but they can be pooled from donated human blood and given by injection.

The type of immunoglobulin used for ITP is called immunoglobulin G (IgG). It's given intravenously, usually over two to five days.

The precise action of IgG in ITP is unknown, but it's thought to block platelet removal and so increase their number. IgG treatment provides only a temporary response, so it is mainly of benefit in acute ITP.

In chronic ITP it may be used when a temporary rise in platelets is desired or during pregnancy because the risk to the baby is less than with other treatments.

Anti-D antibody

An alternative approach is to use anti-D, which contains antibodies to the rhesus blood group protein 'D'. This works in a similar way to IgG, but is administered as a single injection that can be repeated. Many centres now give anti-D instead of IgG, because it is equally effective and simpler to give.

Alternative treatments for ITP

These include:

- other forms of immune suppression with drugs such as cyclophosphamide, azathioprine, vincristine, danazol, cyclosporine A and mycophenolate
- repeated short doses of a steroid known as dexamethasone.

It usually takes two to three months before azathioprine and cyclophosphamide have any effect on the platelet count. During this time they should be carefully monitored, because they have other toxic effects such as disturbed liver function, bone marrow suppression and effects upon fertility.

Mycophenolate can also be slow acting in ITP. Again, you should be monitored for side-effects such as abnormal blood count (usually low white cell count) or abnormal liver function tests. In some people this drug causes problems in the stomach and intestine.

Danazol is a synthetic androgen (male hormone-like drug). It is successful for about half of those patients who do not respond to other treatment, but has to be used with caution. Its side-effects include abnormal liver function, acne, weight gain and increased body hair.

Cyclosporin A is a drug that suppresses certain aspects of the immune system. It is often used in patients who have had a transplant to prevent rejection of the organ. Some people with chronic ITP achieve a response to this drug.

You will need monitoring on this medicine: it can increase blood pressure and worsen kidney function. Some patients who are on cyclosporine for a long time develop enlarged gums.

Removal of the spleen (splenectomy)

The spleen sits under the rib cage on the left side of the abdomen. One of its functions is to remove old red blood cells. In most patients with ITP, it is the main site of platelet destruction.

In chronic ITP, surgery to remove the spleen is an option if the platelet count remains too low or doesn't respond to treatment. Only about 10 per cent of children with acute ITP have the operation.

Removing the spleen is a major operation and usually requires 7 to 10 days in hospital, although some surgeons are now able to remove the spleen using keyhole surgery. About two thirds of patients respond to splenectomy, but some of these eventually relapse.

Splenectomy is not generally considered in the early phases of ITP, in pregnancy or in children under six.

Vaccinations given Streptococcus pneumoniae which causes pneumonia.

Haemophilus influenza type B, which can cause serious infection of the airways.

Meningococcal vaccine, against the organism which causes bacterial meningitis.

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