Immune thrombocytopenic purpura (ITP) affects both children and adults. It is an autoimmune disorder characterised by persistent thrombocytopenia (peripheral platelet count of less than 150 x109/L) due to autoantibody binding to platelet antigen(s) causing their premature destruction by the reticuloendothelial system, in particular the spleen.
In childhood, the peak age is 2-4 years, girls and boys are equally affected, and in most children the disease is self-limiting with spontaneous recovery occurring in several weeks to several months. In adults, ITP is most common among young women and the disease is more insidious in its onset and chronic in its course 1 Level 9. The true incidence of ITP is still unknown. In children, the overall incidence of ITP is 4 – 5.3 per 100,000 2 Level 8 ; 3 Level 6. It has been reported that the incidence of chronic adult ITP is around 5.8-6.6 new cases per 100,000 population per year in the USA 4 Level 9.
2. ITP IN ADULTS
2.1 Clinical Features
In adults, ITP typically has an insidious onset, with no prodromal illness. Symptoms and signs are highly variable, ranging from the common asymptomatic patient with mild bruising or mucosal bleeding to frank haemorrhage from any site, the most serious of which is intracranial. The most common manifestation in ITP is mucocutaneous bleeding with purpura, epistaxis, gingival bleeding and menorrhagia. Overall, bleeding symptoms are uncommon unless the ITP is severe (platelet count < 30×109/ l) 1 Level 9. The degree of bleeding is largely dependent on the platelet count and patients with platelet counts below 10×109/l (and usually below 5×109/l) are at greatest risk of bleeding, including intracranial haemorrhage.
There is no gold standard diagnostic test to confirm ITP. The diagnosis of ITP remains clinical and is based principally on the exclusion of other causes of thrombocytopenia by the history, physical examination, full blood count, peripheral blood film and autoimmune screen.