Thrombocytopenia

– A platelet disorder in which the platelet count falls below 200,000/mm3, leading to bleeding into the skin, mucous membranes, internal cavities, and organs.

Causes and Incidence

Thrombocytopenia may be idiopathic, or it may occur secondary to another process that reduces the number of platelets or produces defective platelets. These processes include use of drugs that can cause platelet destruction (heparin, quinidine, sulfa, oral hypoglycemics, gold salts, rifampin); underlying disease (leukemia, aplastic anemia, cirrhosis, disseminated intravascular coagulation); severe infection; hypothermia; hypersplenism; and alcohol ingestion. Idiopathic thrombocytopenia purpura (ITP) may be either acute or chronic. The acute form usually follows a viral infection such as rubella or chicken pox and affects mostly children between 2 and 6 years of age. The chronic form is linked to immunologic disorders such as lupus and HIV and usually affects adults of all ages, particularly women.

Disease Process

ITP is thought to be associated with an autoimmune process in which the platelets are prematurely destroyed by circulating antibodies. The pathophysiology in secondary forms of the disease is related to the causative agent.

Symptoms

Common manifestations include petechiae and ecchymoses on the skin, particularly the lower extremities; easy bruising; bleeding from the nose and gums; melena in stools; hematemesis; heavy menses and breakthrough bleeding; and hematuria.

Potential Complications

Complications include hemorrhage into organs such as the brain, gastrointestinal tract, or heart, which can be fatal without treatment.

Diagnostic Tests

Other platelet disorders must be ruled out.

Platelets
Count decreased; size and morphologic appearance may be abnormal in ITP

Platelet survival
To help distinguish between ineffective and inappropriate platelet production

Bone marrow
Abundance of megakaryocytes

Bleeding time
Prolonged

Coagulation time
Normal

Capillary fragility
Increased

Treatments

Surgery
Splenectomy for severe thrombocytopenia related to hypersplenism or splenomegaly.

Drugs
Corticosteroids to enhance platelet production and promote capillary integrity; immunosuppressants when disease does not respond to steroids; immune globulin to prepare severely thrombocytic individuals for surgery; discontinuing any drug that may be causing the disorder.

General
Platelet transfusions for severe bleeding; safety precautions to prevent bruising; balance of rest and activity; monitoring for bleeding episodes; instruction in infection precautions for those taking immunosuppressants.