Idiopathic Thrombocytopenic Purpura (ITP) - Pearls

• ITP differs in its presentation in adults vs children.  In children; acute ITP often follows viral illness and usually spontaneously resolves. However, in adults, it is more of a chronic disease and complete remission is uncommon.
• Clinical manifestations: time course of insidious (may be associated with history of infection)
• Signs and symptoms: petechiae, purpura, easy bruising, epistaxis, gingival bleeding (purpura are non-palpable, and localize to dependent regions)
• Suspect ITP in a patient with isolated thrombocytopenia with an otherwise normal smear.  The most important thing to remember is that ITP is a diagnosis of exclusion.  At the minimum, all patients should be ruled out for HIV and Hep C; all patients 60 years or older should have a bone marrow biopsy to exclude Myelodysplastic syndrome as well as other hematological malignancies. 
• Antiplatelet Antibodies are neither sensitive nor specific, and thus are not recommended to be checked.

Treatment: Generally, should treat all adults with platelet count <30 k, as remission is unlikely.  Patients with platelet count > 30k usually have a benign course without treatment.

1) Steroids – 1st line, patients usually respond within 2 weeks, but patients tend to recur once tapered.

2) IVIG – usually used with steroids; effect is seen within days and lasts weeks.  But again, this is a temporizing measure.

3) Splenectomy – thought to be the most effective therapy with the most durable response.  Induces long-term remission in ~66% of patients.  Of course, the problem is that often the patients who most urgently need splenectomy have severely low platelet counts, precluding surgery.  

4) Rituximab – short-term effectiveness in ~40%.  Usually reserved for patients who recur after splenectomy.

5) TPO Agonists – Romiplastin and Eltrombopag – the newest agents on the block - stimulate the bone marrow to increase platelet production.  Positive data from randomized controlled trials, but problem is that does not induce long-term response and so patients are often on them indefinitely.  There are also concerns about long-term safety, as patients can get deposition of reticulin in the bone marrow, potentially raising the risk of myelofibrosis and other malignancies. Romiplostim carries risk of BM fibrosis, and eltrombopag risk of thrombosis

(Christopher Woo MD, 6/9/11)

(Chanu Rhee MD, 2/18/11)