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31 Cards in this Set
- Front
- Back
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What are the 5 major effects of platelet activation?
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• local release of ligands essential to stabilizing platelet matrix • continued recruitment of additional platelets • vasoconstriction of smaller arteries • increased platelet-associated fibrin formation • protection of clot from fibrinolysis
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What are the two pathways of the coagulation cascade?
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• Extrinsic (PT) pathway • Intrinsic (PTT) pathway
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The "PT" is highly sensitive to deficiencies of which factors?
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Factors II (Prothrombin), V, VII, X
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What is the most sensitive test to measure the therapeutic efficacy of warfarin (Coumadin)?
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PT
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What test is very sensitive to measuring heparin?
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PTT
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What is a purpose of a mixing study?
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enables one to distinguish between factor deficiency and a circulating inhibitor
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What is the definition of vascular purpura?
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• bleeding caused by intrinsic strucutla abnormalities of blood vessels OR • by inflammatory infiltration of blood veseels
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What are 3 general causes of thrombocytopenia?
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• decreased platelet production • increased platelet sequestration • increased peripheral platelet destruction
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What are some causes of decreased platelet production?
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• Nutritional causes (B12/Folate deficiency) • Congenital causes • Marrow damage & destruction of stem cells • Invasivce malignant disease or infection • Metabolic abnomalities affecting megakaryocyte maturation
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What is platelet sequestration?
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conditions that lead to splenomegaly that cause increased trapping of platelets
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Platelet sequestration is common in what diseases?
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• advanced liver disease • myeloproliferative disorders • malignant disease invloving the spleen
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True/False: Thrombocytopenia caused by autoimmune disorders generally involve a dramatic increase in marrow megakaryocytes and increased marrow platelet production
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The correct answer is: True
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What does an increased percentage of reticulated platelets indicate?
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immune-mediated thrombocytopenia indicating platelet destruction
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This disorder is often preceded by a viral infection and can resolve without therapy in children?
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Acute Immune Thrombocytopenic Purpura (ITP)
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How do patients with ITP present?
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• petechial hemorrages • mucosal bleeding • thrombocytopenia (< 20,000/µL)
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What are lab results for a patient with ITP?
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• peripheral smear shows large platelets & increased percentage of reticulated platelets (with no other abnormal cells) • bone marrow shows increased (or occasionally normal) numbers of megakaryocytes • presence of platelet autoantibodies in serum
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What is the treatment of acute ITP?
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• Steroids • Intravenous immunoglobin (IVIG)
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What are some drugs that can cause ITP?
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• Quinidine or quinine-based drugs • Sulfa Drugs • Psychotropic drugs • Gold Salts
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What is the most severe complication of Heparin-induced thrombocytopenia (HIT)?
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thromboembolism
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What are causes of Disseminated Intravscular Coagulation (DIC)?
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• Sepsis or endotoxin • Tissue damage • Malignant Disease (adenocarcinoma, acute promyelocytic leukemia) • Primary Vascular Disorders (vasculitis, giant hemangioma, aortic aneurysm) • Exogenous causes
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What is the classic pentad of signs for TTP?
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• fever • thrombocytopenia • microangiopathic hemolysis • neurologic symptoms • renal insufficiency
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How does Hemolytic Uremia Syndrome differ from TTP?
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• HUS presents with renal failure (marked increased in BUN/Cr) without neurological symptoms
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True/False: HUS is primarily seen in adults and TTP is primarily seen in children
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HUS is primarily seen in children, where as TTP is mostly seen in adults The correct answer is: False
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What is the HELLP syndrome?
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A syndrome in pregnant women characterized by: • Hemolysis • Elevated Liver Enzymes • Low Platelet counts in association w/ preeclampsia
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What are characteristics of the Antiphospholipid Syndrome?
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• not associated with bleeding • characterized by destructive thrombocytopenia, recurrent thrombosis, or fetal loss
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How is antiphospholipid syndrome diagnosed?
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by the demonstration of a lupus anticoagulant and/or anticardiolipin antibody
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What causes thrombocytopenia in the antiphospholipid syndrome?
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increased peripheral platelet destruction due to vascular angiopathy and increased platelet consumption in the microvasculature
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What is the function of fibrinogen?
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functions as a bridging ligand for the the platelet receptor GP IIB/IIIA in the platelet-platelet matrix at sites of vascular damage
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What is dysfibrinogenemia?
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an abnormal fibrinogen protein
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What are causes of Vitamin K deficiency?
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• biliary tract disease that interferes with enterohepatic circulation & leads to decreased absorption of vitamin K • drugs (antibiotics, cephalosporins) • poor nutritional status
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Patients with liver disease have low levels of nearly all factors except _____.
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Factor VIII
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