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