Idiopathic Thrombocytopenia Purpura

At a glance

Autoimmune disease resulting in destruction of platelets and presenting as bleeding disorders. Idiopathic thrombocytopenic purpura (ITP) commonly occurs in young females of reproductive age group. The major complication of ITP is peripartum hemorrhage. Neonatal thrombocytopenia or hemorrhage is uncommon. Two distinct clinical syndromes manifest as an acute condition in children and a chronic condition in adults, particularly women. The acute form often follows an infection and has a spontaneous resolution within 2 months. Chronic immune thrombocytopenia persists longer than 6 months with a specific cause being unknown.

Synonyms

Immune Thrombocytopenic Purpura; Werlhof Disease.

Incidence

Acute: 6:100,000 per year in the general population. No sex predilection. Peak incidence occurs between 2 and 4 years of age. Chronic: 1:250,000 per year in the general population. Females affected two to three times more often than males. Peak incidence occurs between 20 and 50 years of age.

Genetic inheritance

Not a genetic disorder. However, the development of antiplatelet antibodies in idiopathic thrombocytopenia purpura seems to be driven by an encounter with several platelet antigens through the clonal expansion of B cells using genetically restricted and highly specific combinations of heavy- and light-chain gene products.

Pathophysiology

The majority of patients have circulating antiplatelet antibodies, directed at glycoproteins IIb and IIIa, leading to platelet destruction in the spleen and thrombocytopenia. Although platelet production is increased, it does not prevent thrombocytopenia.

Diagnosis

Patients develop petechiae, bruising, and nosebleeds, usually after a viral illness. The remainder of the physical examination is normal. All laboratory tests are normal, with the exception of a markedly decreased platelet count and increased bleeding time. The platelet count is the only test needed to confirm the clinical diagnosis.

Clinical aspects

Petechiae, easy bruising, nosebleeds, and thrombocytopenia. Typically, course is benign with excellent prognosis. Treatment includes steroids, intravenous immunoglobulin (IV immunoglobulin), anti-D immunoglobin, chemotherapeutic agents, plasmapheresis, and splenectomy in refractory cases. Complications include intracranial hemorrhage (0.1-0.5%), usually with platelet counts below 20,000/mm³. Fetal thrombocytopenia is secondary to transplacental crossing of antiplatelet antibodies. There are two forms of idiopathic thrombocytopenia purpura:

• Acute Form: Encountered in children ranging in age from 2 to 6 years, often after a viral illness. It usually has a sudden onset and disappears within a few weeks (<6 months).

• Chronic Form: Occurs at any age but is more common in women of childbearing age. It lasts more than 6 months (often several years) and requires continual follow-up care.

Precautions before anesthesia

Consult hematologist regarding intravenous immunoglobulin and anti-D immunoglobulin. Check platelet count. Type and cross for platelets in emergency surgery (type and cross helps prevent alloimmunization in ...