Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder characterized by too few platelets (thrombocytopenia) in the blood Platelets are necessary for normal blood clotting by clumping together to plug small holes in damaged vessels.The disease occurs when immune system produces antibodies against platelets. The presence of antibodies on platelets leads to their destruction in the spleen. In children, the disease is often follows a viral infection within the preceding three weeks. In some children it can become a chronic (long-term) disease. It is most common in children between the ages of two and six years.

What does it look like?

• Bruising
• Nosebleed or oral bleeding
• Bleeding into the skin - also called pinpoint red spots and petechiae
• Abnormally heavy menstruation
• Gastrointestinal bleeding
• Blood in the urine (hematuria)
• Bleeding into the brain (Intracranial haemorrhage occurs in 0.1 - 0.5% of cases of acute ITP)

The tests used to diagnose ITP include:

• Complete blood count (CBC) shows low platelet count.
• Bone marrow examination is only indicated if the history, physical examination (enlarged lymph nodes or spleen), blood count (neutropenia, anaemia) or blood film is atypical. Bone marrow aspiration or biopsy appears normal in ITP.
• PTT (coagulation studies) is normal.
• PT (coagulation studies) is normal.
• Platelet associated antibodies may be detected.
• Auto-immune screen may be helpful in chronic cases (particularly adolescent girls)

The treatment of ITP depends on the degree of platelet reduction in the blood. Platelet counts below 50,000/mm3 increase the risk of dangerous bleeding from trauma; counts below 20,000/mm3 increase the risk of spontaneous bleeding. The main reason for treating children with acute ITP is the prevention of intracranial hemorrhage (ICH), a complication that occurs in 1% of affected children.In some children the disease often runs its course without treatment. 50% of children recover in 3-4 weeks, 75% in 6 months, 90% within 12 months. Chronic ITP is arbitrarily defined as thrombocytopenia that persists for 6 months or more.

Treatment should be given to children who have:

• platelet counts less than 20,000/mm3
• evidence of mucosal bleeding (e.g. petechiae of the soft palate or inside the mouth)
• haematuria or retinal haemorrhages
• a need for urgent increase in platelet count (e.g. emergency surgery or suspected intracranial haemorrhage.

The two main alternatives for treatment are either intravenous immunoglobulin (IVIG) or high-dose oral Prednisone. A minority of children may not respond to either therapy. In those who do respond, there is a risk of relapse in up to 25% of cases with either therapy. Intravenous gammaglobulin is often the treatment of first choice and can be given as a single dose. It may raise the platelet count more quickly and more predictably than Prednisone, thus resulting in earlier discharge from hospital. It avoids the potential side effects associated with high dose oral Prednisone.Transient side effects of headache, fever and nausea may be seen during the course of the infusion. Oral Prednisone can be used in a high dose of 4 mg / kg / day for 7 days and avoids potential problems with the use of a blood product such as IVIG.

A less commonly used therapy is with Anti-RhD (antibody to Rh factor on red blood cells) which can also be useful in people with specific blood types.

Ocassionally ITP may become a chronic ailment and reappear, even after remission. A splenectomy (removal of the spleen) is sometimes advised since the spleen is the major site of platelet destruction. In most instances, splenectomy is performed in children in whom thrombocytopenia has persisted for more than 1 year and who have clinically important bleeding. Most children undergoing elective splenectomy achieve a complete remission from ITP after splenectomy.

People with ITP should avoid taking aspirin, ibuprofen and warfarin because these drugs interfere with platelet function and blood clotting, and bleeding may occur. Intramuscular injections are contraindicated and rough play should be discouraged when the platelet count is low.

Follow-up of children who have been successfully treated should include regular blood counts until their platelet count has returned to 150,000/mm3 or above. They may be followed up by their family doctor and no further platelet counts are needed unless clinical signs of bruising or bleeding return.