Immune Thrombocytopenic Purpura (ITP)

Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder that is characterized by abnormally low levels of blood platelets (thrombocytopenia). In most cases, the low platelet level in ITP develops because the immune system mistakes platelets as foreign substances and attacks them. However, ITP can also be caused by an underlying condition (e.g. chronic infections, lymphomas, or an auto-immune disorder) leading to an auto-immune mediated decrease in the platelet level.

ITP can either be acute, or chronic. Acute ITP is the most common of the 2 ITP subtypes and usually affects young children (2 to 6 years old). Acute ITP often develops following a viral infection, such as chickenpox. This form of ITP usually starts suddenly, and the symptoms usually disappear in a couple of weeks. Treatment is generally not needed, and the disorder does not tend to recur.

In contrast, chronic ITP can occur at any age, with a slight predominance for women, and symptoms persist for many years (or even lifelong). Chronic ITP is also characterized by regular recurrences and therefore requires follow-up by a hematologist.

For the moment, there is no definitive laboratory test to diagnose ITP. In fact, ITP is a “diagnosis of exclusion” meaning that other causes have been considered and are either eliminated or unlikely.

In addition to a complete medical history and a physical exam, the diagnostic work-up for ITP includes a complete blood count to measure the size, number, and maturity of the different cells in the blood. Additional blood and urine tests will look for possible infections (e.g., hepatitis C, helicobacter pylori, etc.). In addition to this, physicians will do a careful review of the medication a patient is taking.

Children with ITP usually have mild symptoms and generally don’t need any treatment. For adults, however, treatment is often warranted. In brief, this treatment aims at boosting the production of platelets and preventing the immune system from attacking red blood cells.

The most commonly used agents to silence the immune system consist of corticosteroids and immunosuppressants. In addition to this, intravenous gamma globulin (IVGG) can be given to slow down the destruction of platelets. In addition, also the monoclonal antibody rituximab has a place in the treatment of ITP. To increase the production of platelets, thrombopoietin receptor agonists such as romiplostim, eltrombopag or avatrombopag are used in ITP patients.

If these medications don’t work, patients may need to have their spleen surgically removed (splenectomy). The reason for this is that the spleen is the organ where most of the red blood cell destruction is taking place.