IDIOPATHIC THROBOCYTOPENIC PURPURA (ITP)

• Pathological Basis:
  • Mechanism of this disorder: immune system mediated destruction of platelets.
  • Platelets in patients with ITP have a shortened life span. However, circulating platelets are hemostatically active.
  • There are two forms of ITP: acute and chronic:
    • Acute ITP: relatively common during childhood. The maximal incidence is between 2 and 5 years of age. It occasionally occurs during childhood as well. There appears to be some correlation with prior viral infection. Acute ITP is characteristically fulminant, with the initial platelet count ranging from zero to 20,000/microliter. Typically, the bone marrow has an increased number of megakaryocytes, which frequently have an immature appearance. Acute ITP usually subsides without treatment within 3 weeks. Patients who do not recover within 6 months are diagnosed as having chronic ITP.
    • Chronic ITP: most patients are between 20 and 50 years of age. There is a predilection for females, the sex ratio is approximately 3:1. Spontaneous remission is relatively rare. Chronic ITP often has an insidious onset.
• Treatment:
  • For acute ITP: a short course of corticosteroids during the first few days of the disease, with IV Ig if bleeding is prominent. Platelet transfusions should only be used for life-threatening situations such as intracranial hemorrhage.
  • For chronic ITP: patients with mild cases respond readily to corticosteroid therapy. Approximately 1 to 1.2 mg of Prednisone per kg of body weight is used as starting dosage. In patients who continue to have symptoms, Rituximab and splenectomy may be considered.