Immune thrombocytopenia (ITP) is an acquired disorder characterized by isolated thrombocytopenia with a peripheral blood platelet count <100 × 109/L in the absence of any obvious initiating or underlying cause. It is a diagnosis of exclusion.
It can be idiopathic or secondary (i.e. due to a connective tissue disease, lymphoma etc). Auto-antibodies have been identified against specific platelet glycoproteins.
List the therapies that can be used in ITP.
- Steroids are the first line of therapy with either the use of prednisone (0.5 mg -2 mg/kg) or a short course of dexamethasone (i.e. 40 mg x 4 days). Studies are ongoing of which regiment gives superior results, however a durable platelet response rate is seen in 70% of patients.
- IVIG results in an acute platelet rise usually within 48 hours of use with an effect lasting up to 14 days. RhIg can also be considered in non-splenectomized Rh+ patients with no evidence of hemolysis.
- Splenectomy: controversy exists on when to recommend splenectomy, however this is usually reserved for steroid refractory patients with a 20% relapse rate
- Rituximab: anti-CD20 monoclonal antibody with a durable response at one year seen in 1/3 of patients. The optimal dosing strategy is unknown.
- Thrombomimetics: tpo receptor agonists
- currently only available once two lines of therapy have been exhausted (including splenectomy), unless contraindicated
Liebman HA et al. Diagnosis and Management of Immune Thrombocytopenia in the Era of Thrombopoietin Mimetics. ASH Education Handbook 2011.