What is Idiopathic Thrombocytopaenic Purpura (ITP)

Idiopathic thrombocytopenic purpura is a disease involving immune destruction of platelets. Platelets are cells present in the blood which are important in forming ‘plugs’ in damaged vessels to stop bleeding, while the longer process of clotting occurs. In ITP, destruction of platelets leads to an increased tendancy to bleed.

Statistics on Idiopathic Thrombocytopaenic Purpura (ITP)

According to studies in Denmark and England, childhood ITP occurs in approximately 10-40 cases per 1,000,000 per year. A study in Kuwait reported a higher incidence of 125 cases per 1,000,000 per year

Risk Factors for Idiopathic Thrombocytopaenic Purpura (ITP)

The word ‘idiopathic’ means of unknown cause. While the precise mechanism of the development of the disease has not been found, the disease is associated with the following factors:

  • Viral infection in children
  • Autoimmune diorders in adults, such as thyroid disease, autoimmune haemolytic anaemia (Evan’s syndrome)
  • Chronic lymphocytic leukaemia, solid tumours
  • Viral infections such as HIV

Progression of Idiopathic Thrombocytopaenic Purpura (ITP)

Acute ITP is usually seen in children, often following a viral infection. The disease usually remits (disappears) spontaneously.

Chronic ITP is characteristically seen in adult women. Chronic ITP is unlikely to go away on its own.

How is Idiopathic Thrombocytopaenic Purpura (ITP) Diagnosed?

Full blood count – this blood test will reveal ‘thrombocytopaenia’, or low platelet count.

Prognosis of Idiopathic Thrombocytopaenic Purpura (ITP)

Prognosis is good for acute ITP, and most make spontaneous recovery.

Chronic ITP patients almost always require treatment. Even with treatment, relapse commonly occurs.

Complete response to first line steroid treatment occurs in 20%; 60% have partial response. The 20% who fail, as well as about half of the partial responders, will require a splenectomy. This procedure has a high response rate (90%), but 30% of these will eventually relapse.

How is Idiopathic Thrombocytopaenic Purpura (ITP) Treated?

Acute ITP

treatment is usually not required, as the disease remits spontaneously. In severe cases, steroids or high-dose intravenous immunoglobulin is required.

Chronic ITP

treatment is usually required. Initial treatment is with the steroid prednisolone, which is reduced in dose after remission has occurred. Approximately half will not need any further treatment. The other half, however, suffer continued disease, and will require splenectomy (removal of the spleen). This is 90% effective in curing the disease. In a few patients, further immunosuppressive medication, such as azathioprine, cyclophosphamide or vincristine may be required.

Idiopathic Thrombocytopaenic Purpura (ITP) References

  1. Kumar P, Clark M. Clinical Medicine. Fourth Ed. WB Saunders, 1998. pp 402-403