Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura is a bleeding disorder in which the blood does not clot properly. The bleeding is due to a low number of platelets. Platelets help the blood clot and stop bleeding. People with idiopathic thrombocytopenic purpura often have purple bruises that appear on the skin.

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, autoimmune thrombocytopenia). Acute ITP usually affects children between ages 2 and 6; chronic ITP mainly affects adults under age 50, especially women between ages 20 and 40.

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

Idiopathic means no known cause. However, when a cause can be identified, it may be a result of the following:

• medications (including over-the-counter medications)
• infection
• pregnancy
• immune disorders

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 and without warning, causing easy bruising, epistaxis, and bleeding gums. Onset of chronic ITP is insidious.

Diagnosis

ITP is usually considered a diagnosis of exclusion, which means that the doctor arrives at the diagnosis by a process of ruling out other possible causes. If the patient belongs to one or more of the risk groups for chronic ITP, the doctor may order a blood test for autoantibodies in the blood early in the diagnostic process.

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 I to 4 months or who need high steroid dosage are candidates for splenectomy, which has an 85% success rate. Alternative treatments include immunosuppression, high-dose I.V. gamma globulin, and immunoabsorption apheresis using staphylococcal protein-A columns.

CLINICAL TIP

Before splenecto my, 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.

Prevention

The causes and risk factors are unknown (except in children when it may be related to a viral infection). Therefore, prevention is unknown.