Idiopathic thrombocytopenic purpura
Idiopathic thrombocytopenic purpura (ITP), thrombocytopenia that results from immunologic platelet destruction, may be acute (postviral thrombocytopenia) or chronic (Werlhof’s disease, purpura hemorrhagica, essential thrombocytopenia, and autoimmune thrombocytopenia). The prognosis for acute ITP is excellent; nearly four out of five patients recover without treatment. The prognosis for chronic ITP is good; remissions lasting weeks or years are common, especially among women.
Causes and incidence
ITP may be an autoimmune disorder, because antibodies that reduce the life span of platelets have been found in nearly all patients. The spleen probably helps to remove platelets modified by the antibody. Acute ITP usually follows a viral infection, such as rubella or chickenpox, and can follow immunization with a live virus vaccine. Chronic ITP seldom follows infection and is commonly linked to immunologic disorders such as systemic lupus erythematosus. It’s also linked to drug reactions. ITP frequently occurs in patients who have abused alcohol, heroin, or morphine, and in patients with acquired immunodeficiency syndrome who are exposed to the rubella virus.
Acute ITP usually affects children between ages 2 and 6; chronic ITP mainly affects adults younger than age 50, especially women between ages 20 and 40.
Signs and symptoms
Clinical features of ITP common to all forms of thrombocytopenia include petechiae, ecchymoses, and mucosal bleeding from the mouth, nose, or GI tract. Generally, hemorrhage is a rare physical finding. Purpuric lesions may occur in vital organs, such as the lungs, kidneys, or brain, and may prove fatal. In acute ITP, which commonly occurs in children, onset is usually sudden, causing easy bruising, epistaxis, and bleeding gums. Onset of chronic ITP is insidious.
Diagnosis
Platelet count less than 20,000/µl and prolonged bleeding time suggest ITP. Platelet size and morphologic appearance may be abnormal; anemia may be present if bleeding has occurred. As in thrombocytopenia, bone marrow studies show an abundance of megakaryocytes and a shortened circulating platelet survival time (hours or days). Occasionally, platelet antibodies may be found in vitro, but this diagnosis is usually inferred from platelet survival data and the absence of an underlying disease.
Treatment
Acute ITP may be allowed to run its course without intervention or may be treated with glucocorticoids or immune globulin. For chronic ITP, corticosteroids may be the initial treatment of choice. Patients who fail to respond within 1 to 4 months or who need high steroid dosage are candidates for splenectomy, which may be successful in 50% of cases. Alternative treatments include immunosuppression, high-dose gamma globulin injections, and immunoabsorption apheresis using staphylococcal protein-A columns, which filter antibodies out of the bloodstream. Anti-RhD therapy can also be useful in people with specific blood types.
Before splenectomy, the patient may require blood, blood components, and vitamin K to correct anemia and coagulation defects. After splenectomy, he may need blood and component replacement and platelet concentrate. Normally, platelets increase spontaneously after splenectomy.
Special considerations
Patient care for ITP is essentially the same as for other types of thrombocytopenia, with emphasis on teaching the patient to observe for petechiae, ecchymoses, and other signs of recurrence. Monitor patients receiving immunosuppressants for signs of bone marrow depression, infection, mucositis, GI ulcers, and severe diarrhea or vomiting. Tell the patient to avoid aspirin, ibuprofen, and warfarin, as these drugs interfere with platelet function and blood clotting.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Clotting symptoms
» Next page: Purpura (Professional Guide to Signs & Symptoms (Fifth Edition))
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