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Autoimmune disease resulting in destruction of
platelets and presenting as bleeding disorders.
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Idiopathic Thrombocytopenic Purpura; Werlhof Disease.
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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.
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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 heavyand light-chain gene products.
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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.
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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.
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Petechiae, easy bruising, nosebleeds,
thrombocytopenia. Typically course is benign with excellent prognosis.
Treatment includes steroids, intravenous 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:
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- 1. Acute form is 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 (less than 6 months).
- 2. Chronic form can occur 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.
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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 patients with frequent transfusions).
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Bleeding usually does not occur with
platelet counts greater than 50,000/mm3. The decision to transfuse
platelets should be based on clinical bleeding, not actual platelet count.
Central-neuraxial anesthesia is contraindicated because of the risk of
hematoma. Some patients have undergone splenectomy, which makes them more
prone to develop infection. Administration of perioperative corticosteroid
supplementation is highly recommended.
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Administration of pharmacological
agents that affect platelet adhesion (e.g., aspirin) should be avoided. If
anticoagulation is needed, extreme precautions are needed during
administration (e.g., bleeding time, coagulation profile). Although some
patients (e.g., children with the acute form) do not receive any treatment,
most patients affected with this condition are given drugs that can affect
the ...