What is the pathogenesis and incidence of ITP?

ITP is believed to be caused by one or more antiplatelet autoantibodies that cause accelerated platelet destruction by the mononuclear phagocytic system, primarily in the spleen.

In children ITP is usually an acute, self-limited disorder that resolves spontaneously whereas in adults it is typically a chronic disorder.

Reports indicate that about 5% of patients with ITP may die of hemorrhagic complications (e.g., intracranial hemorrhage) but these studies were done before current therapies were available.

The reported prevalence of ITP in adults and children is 1 to 13 per 100,000 persons. Adult chronic ITP is a relatively common autoimmune disorder with 14,000 to 16,000 new cases occurring each year in the United States.