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Пульмонология, гематология (англ,рус)

·        spleen is of normal size unless it is enlarged by a coexistent childhood viral infection.

·        ITP is suspected in patients with unexplained thrombocytopenia. Peripheral blood is normal except for reduced platelet numbers.

·        Bone marrow is examined if blood counts or blood smear reveals abnormalities in addition to thrombocytopenia. Bone marrow examination reveals normal or possibly increased numbers of megakaryocytes in an otherwise normal marrow.

·        Because diagnostic findings are nonspecific, diagnosis requires exclusion of other thrombocytopenic disorders suggested by clinical or laboratory test data.

·        Because HIV-associated thrombocytopenia may be otherwise indistinguishable from ITP, HIV testing is performed if the patient has risk factors for HIV infection.

 

 

 

Treatment includes of ITR

·        Corticosteroids (prednisone 1 mg/kg once/day) initially. In the patient who responds, the platelet count rises to normal within 2 to 6 wk).

·        Splenectomy (can achieve a remission in about 2⁄3 of these patients),

·        Immunosuppressive treatment (cyclophosphamide, azathioprine, rituximab),

·        Platelet transfusions,

·        IV immune globulin. In a child or adult with ITP and life-threatening bleeding, rapid phagocytic blockade is attempted by giving IV immune globulin 1 g/kg once/day for 1 to 2 days. This usually causes the platelet count to rise within 2 to 4 days but only for 2 to 4 wk.

 

Thrombocytopenia: Other Causes

·        Acute respiratory distress syndrome

·        Blood transfusions

·        Connective tissue and lymphoproliferative disorders

·        Drug-induced immunologic destruction (Quinidine, sulfa preparations, carbamazepine, methyldopa, aspirin, oral antidiabetic drugs, gold salts, and rifampin, heparin)

·        Gram-negative sepsis

·        HIV 

 

Thrombocytopenia Due to Splenic Sequestration

Increased splenic platelet sequestration can occur in various disorders that produce splenomegaly. Sequestration is expected in patients with congestive splenomegaly caused by advanced cirrhosis. The platelet count usually is > 30,000/μL unless the disorder producing the splenomegaly also impairs platelet production (eg, in myelofibrosis with myeloid metaplasia).

 

Thrombotic Thrombocytopenic Purpura (TTP) and Hemolytic-Uremic Syndrome (HUS)

·        unexplained thrombocytopenia and microangiopathic hemolytic anemia are sufficient evidence for a presumptive diagnosis.

·        TTP-HUS is suspected in patients with suggestive symptoms, thrombocytopenia, and anemia. If the disease is suspected, urinalysis, peripheral blood smear, reticulocyte count, serum LDH, renal functions, serum bilirubin (direct and indirect), and Coombs' test are obtained. The diagnosis is suggested by thrombocytopenia and anemia, with fragmented RBCs on the blood smear (helmet cells, triangular-shaped RBCs, distorted-appearing RBCs-these changes describe microangiopathic hemolysis); evidence of hemolysis (falling Hb level, polychromasia, elevated reticulocyte count, elevated serum LDH); and negative direct antiglobulin (Coombs') test.

 

Prognosis and Treatment

·        Epidemic HUS in children associated with enterohemorrhagic infection usually spontaneously remits and is treated with supportive care and not plasma exchange. In other cases, untreated TTP-HUS is almost always fatal. With plasma exchange, however, about 85% of patients recover completely. Plasma exchange is continued daily until evidence of disease activity has subsided, which may be several days to many weeks

·        Corticosteroids and antiplatelet drugs (aspirin) have also been used but are controversial.

 

Coagulation Disorders  Caused by Circulating Anticoagulants (CA)

·        CA are usually autoantibodies that neutralize specific clotting factors in vivo (autoantibody against factor VIII or factor V) or inhibit protein-bound phospholipid in vitro;

·        antibodies bind to prothrombin-phospholipid complexes, inducing hypoprothrombinemia; these patients may bleed excessively;

·        Factor VIII autoantibodies also arise occasionally in nonhemophilic patients, eg, in a postpartum woman as a manifestation of underlying systemic autoimmune disease or in elderly patients without overt evidence of other underlying disease. Patients with a factor VIII anticoagulant can develop life-threatening hemorrhage.

·        Therapy with cyclophosphamide and corticosteroids may suppress autoantibody production in patients without hemophilia.

 

Disseminated Intravascular Coagulation(DIC) (Consumption Coagulopathy; Defibrination Syndrome)

DIC involves abnormal, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation factor consumption occur. DIC that evolves slowly (over weeks or months) causes primarily venous thrombotic and embolic manifestations; DIC that evolves rapidly (over hours or days) causes primarily bleeding.

 

Etiology and Pathophysiology of DIC

·        Complications of obstetrics—eg, abruptio placentae, saline-induced therapeutic abortion, retained dead fetus or products of conception, or amniotic fluid embolism.

 

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