Treatment of Acute ITP

Immune (Idiopathic) thrombocytopenic purpura is a disease characterized by platelet destruction and decreased platelet synthesis due to autoantibodies.  The term idiopathic is sometimes used because not all patients with ITP demonstrate these autoantibodies.  The treatment for adults and children are basically the same, although the first line therapy for each is usually different. 

In adults the threshold for treating ITP is typically below 30,000 platelets, even if the patient is asymptomatic.  Most experts agree that asymptomatic adults with platelet counts above 30,000 to 50,000 do not need treatment.  Severe bleeding usually does not occur until the platelet count drops below 10,000.  The management of children is slightly different, as the American Society of Hematology recommends treatment in any child with ITP and either severe bleeding or platelets of less than 10,000.

The first line treatment for adults is usually prednisone or prednisolone at a dose of 1 mg/kg daily, usually for an extended period of time (weeks).  Once the platelet count rises and stabilizes, the steroid may be tapered, but many patients have another drop in platelets at that time.  Two thirds of adult patients have an initial response to the prednisone, although only 1o to 15% have a true remission on long term follow up with just one treatment.  Another steroid currently being investigated for use in ITP is dexamethasone.  The dose is typically 40 mg daily (IV or PO) for four days, with a possible repeat course if needed.  A non-randomized study showed 106 of 125 patients (85%) had an increase of platelets to > 20,000 by day 3 of treatment with a mean platelet count of 100,000 at one week.  50% of the initial responders in this group had remission at 6 months and required no further treatment.  Currently a randomized trial is being planned comparing dexamethasone 40 mg IV x 4 days for three courses to traditional prednisone 1mg/kg per day treatment.  Intravenous high-dose methylprednisolone is another steroid regimen available, which usually results in a rapid increase in platelet values.

IVIG is another treatment option in ITP.  In adults it is usually given when patients have either severe bleeding or are refractory to steroids.  The exact mechanism of IVIG in ITP is not completely known, although most believe it is due to competitively binding the patient’s autoantibodies to platelets and blocking reticulendothelial system (RES) uptake of antibody coated platelets.  The typical dose is 1 g/kg IV daily for 1-2 days.  80% of adults treated with IVIG will have their platelets increase to > 50,000.  Platelets will begin to rise as early as 1 day after treatment, peaking at one week.

In children, IVIG is normally thought of as first line therapy as six studies in over 400 children showed larger number of platelets at 24, 48, and 72 hours in patients treated with IVIG for ITP compared to steroids.  The side effects of IVIG include flu-like symptoms, nausea, vomiting, and fever. These side effects are concerning, as they are very similar to the presentation of an intracranial bleed, which is the worst complication from ITP.  Steroids (usually prednisolone at 1 mg/kg daily) are usually second line in the treatment of ITP in children, although many providers attempt steroids first in children.

Other treatments for ITP include anti-D immunoglobulin, rituximab, and even splenectomy.  Anti-D only works in patients who are Rh positive and still have their spleen; anti-D is given 50 to 75 mcg/kg IV.  The platelet levels usually respond fairly rapidly with this treatment, similar to that of IVIG.  Some shy away from its use due to the 0.7% incidence of intravascular hemolysis after treatment. Interestingly, a small study showed that subcutaneous anti-D immunoglobulin had similar efficacy to the intravenous route, with no incidence of hemolysis.

George J.  Treatment and prognosis of immune (idiopathic) thrombocytopenic purpura in adults.  Uptodate.com.  Updated Mar 20, 2012.

Stasi R. Pathophysiology and therapeutic options in primary immune thrombocytopenia. Blood Transfus. 2011;9:262-73.

Steuber CP. Treatment and prognosis of immune (idiopathic) thrombocytopenic purpura in children.  Uptodate.com.  Updated April 8, 2011.

 

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