Immune Thrombocytopenia Purpura (ITP)

• • Autoimmune destruction of platelets

  • Petechiae, ecchymoses, epistaxis, easy bruising

  • No splenomegaly

  • Decreased platelet count, prolonged bleeding time, poor clot retraction, normal coagulation time

Epidemiology

• • The pathogenesis involves a circulating antiplatelet IgG autoantibody; the spleen is both the site of platelet destruction and a significant source of autoantibody production

  • Idiopathic or secondary to the following:

  • -Lymphoproliferative disorder

    -Drugs or toxins

    -Bacterial or viral infection (especially in children)

    -Systemic lupus erythematosus

    -Other conditions

  • The acute form is most common in children, usually occurring before age 8, and often begins 1-3 weeks after a viral upper respiratory tract illness

  • The chronic form, which may start at any age, is more common in women

Symptoms and Signs

• • Ecchymoses or showers of petechiae

  • Bleeding gums

  • Vaginal bleeding

  • GI bleeding

  • Hematuria

Laboratory Findings

• • Platelet count < 100,000/µL

  • Bone marrow shows increased numbers of large megakaryocytes

  • Bleeding time is prolonged

  • Partial thromboplastin time, prothrombin time, and coagulation time are normal

  • Iron deficiency anemia as a result of bleeding

• • Symptoms often develop when platelet count is < 50,000/µL

  • Recurrent thrombocytopenia after splenectomy can be evaluated by imaging with indium-labeled platelets to identify accessory spleens

  • Chronic ITP characterized by:

  • -An insidious onset

    -A history of easy bruisability and menorrhagia

    -Showers of petechiae, especially over pressure areas

    -Cyclic remissions and exacerbations, which may continue for several years

  • Specific determinations of antiplatelet antibody titers may aid in diagnosis

Rule Out

• • Other causes of nonimmunologic thrombocytopenia:

  • -Leukemia

    -Aplastic anemia

    -Macroglobulinemia

  • Thrombocytopenia and purpura may be caused by:

  • -Ineffective thrombocytopoiesis (pernicious anemia)

    -Nonimmune platelet destruction (septicemia, disseminated intravascular coagulation, hypersplenism)

• • Platelet count

  • Bone marrow biopsy

  • Peripheral blood smear

  • Antiplatelet autoantibody titers if diagnosis remains unclear

When to Admit

• • Severe thrombocytopenia with active bleeding

When to Refer

• • All patients should be managed in conjunction with a hematologist

• • Patients with mild or no symptoms need no specific therapy

  • Splenectomy is most effective therapy

  • No platelet transfusions unless actively bleeding

Surgery

Indications

• • Failure to respond to corticosteroids

  • Relapse after initial remission on corticosteroids

  • Corticosteroid dependence

Medications

• • Corticosteroids

  • Intravenous immunoglobulin (IVIG) for temporary treatment

  • Azathioprine, vincristine

Treatment Monitoring

• • Platelet count

Complications

• • Bleeding

Prognosis

• • Splenectomy: Sustained remission in 60-90% of patients

  • Corticosteroids: Response in 70-80%; sustained remissions in 20% of adults