About Idiopathic Thrombocytopenic Purpura (ITP)
ITP, also known as primary immune thrombocytopenic purpura or autoimmune thrombocytopenic purpura, is an autoimmune disease in which circulating platelets are destroyed.1 ITP can be acute or chronic1,2:
Acute ITP is most often seen in children, of whom approximately 2/3 will recover spontaneously within 6 months. Acute ITP often, but not always, follows a viral infection, and boys and girls are affected equally. It has been demonstrated that an increased risk of ITP is also associated with the measles-mumps-rubella immunization.
Chronic ITP is the form typically seen in adults. It typically has an insidious onset with no preceding viral illness and lasts longer than 12 months.
Signs and Symptoms
Symptoms of ITP can vary widely and its diagnosis is often one of exclusion. Thrombocytopenia can be caused by systemic disease, infection, drugs and primary blood disorders.1,2 ITP is suspected when patient history, physical examination and laboratory blood tests do not suggest another reason for a low platelet count.
Acute ITP presents as the sudden appearance of widespread petechiae and/or purpura in a previously healthy child, with large bruises following minor trauma. Nosebleeds and conjunctival hemorrhages are common. Most children do not require treatment except in the case of a life-threatening hemorrhage, such as a cerebral hemorrhage, which occurs very rarely. Only 10% of acute ITP cases progress to chronic ITP.2
Chronic ITP typically presents gradually, with minor bruising and scattered petechiae. Bleeding episodes are often not frequent and can be separated by months or years.2
Common laboratory tests suggestive of ITP include2:
> Persistent platelet count of less than 40 X 109/L
> Peripheral blood smear may show large platelets or platelet fragments
> Bone marrow examination may show increased megakaryoctyes (suggestive of increased platelet production consequent to the increased rate of platelet destruction in ITP)
> Anemia, if bleeding has occurred
> Direct tests on platelets show the presence of autoantibodies in 90% of patients with ITP
The goal of treatment for ITP is to raise blood platelet counts to a normal range. Treatment may include IGIV, which has been shown to increase platelet counts in patients with ITP.1,2
References: 1. Provan D, Stasi R, Newland AC, et al. International consensus report on the investigation and management of primary immune thrombocytopenia. Blood. 2010;115:168-186. 2. Chapel H, Haeney SM and Snowden N. eds. Non-Malignant Haematological Diseases In: Essentials in Clinical Immunology. 6th ed. John Wiley & Sons, Ltd., West Sussex, UK: John Wiley & Sons; 2014:305-308.