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31 Cards in this Set

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What are the 5 major effects of platelet activation?
• 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
What are the two pathways of the coagulation cascade?
• Extrinsic (PT) pathway • Intrinsic (PTT) pathway
The "PT" is highly sensitive to deficiencies of which factors?
Factors II (Prothrombin), V, VII, X
What is the most sensitive test to measure the therapeutic efficacy of warfarin (Coumadin)?
PT
What test is very sensitive to measuring heparin?
PTT
What is a purpose of a mixing study?
enables one to distinguish between factor deficiency and a circulating inhibitor
What is the definition of vascular purpura?
• bleeding caused by intrinsic strucutla abnormalities of blood vessels OR • by inflammatory infiltration of blood veseels
What are 3 general causes of thrombocytopenia?
• decreased platelet production • increased platelet sequestration • increased peripheral platelet destruction
What are some causes of decreased platelet production?
• Nutritional causes (B12/Folate deficiency) • Congenital causes • Marrow damage & destruction of stem cells • Invasivce malignant disease or infection • Metabolic abnomalities affecting megakaryocyte maturation
What is platelet sequestration?
conditions that lead to splenomegaly that cause increased trapping of platelets
Platelet sequestration is common in what diseases?
• advanced liver disease • myeloproliferative disorders • malignant disease invloving the spleen
True/False: Thrombocytopenia caused by autoimmune disorders generally involve a dramatic increase in marrow megakaryocytes and increased marrow platelet production
The correct answer is: True
What does an increased percentage of reticulated platelets indicate?
immune-mediated thrombocytopenia indicating platelet destruction
This disorder is often preceded by a viral infection and can resolve without therapy in children?
Acute Immune Thrombocytopenic Purpura (ITP)
How do patients with ITP present?
• petechial hemorrages • mucosal bleeding • thrombocytopenia (< 20,000/µL)
What are lab results for a patient with ITP?
• 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
What is the treatment of acute ITP?
• Steroids • Intravenous immunoglobin (IVIG)
What are some drugs that can cause ITP?
• Quinidine or quinine-based drugs • Sulfa Drugs • Psychotropic drugs • Gold Salts
What is the most severe complication of Heparin-induced thrombocytopenia (HIT)?
thromboembolism
What are causes of Disseminated Intravscular Coagulation (DIC)?
• Sepsis or endotoxin • Tissue damage • Malignant Disease (adenocarcinoma, acute promyelocytic leukemia) • Primary Vascular Disorders (vasculitis, giant hemangioma, aortic aneurysm) • Exogenous causes
What is the classic pentad of signs for TTP?
• fever • thrombocytopenia • microangiopathic hemolysis • neurologic symptoms • renal insufficiency
How does Hemolytic Uremia Syndrome differ from TTP?
• HUS presents with renal failure (marked increased in BUN/Cr) without neurological symptoms
True/False: HUS is primarily seen in adults and TTP is primarily seen in children
HUS is primarily seen in children, where as TTP is mostly seen in adults The correct answer is: False
What is the HELLP syndrome?
A syndrome in pregnant women characterized by: • Hemolysis • Elevated Liver Enzymes • Low Platelet counts in association w/ preeclampsia
What are characteristics of the Antiphospholipid Syndrome?
• not associated with bleeding • characterized by destructive thrombocytopenia, recurrent thrombosis, or fetal loss
How is antiphospholipid syndrome diagnosed?
by the demonstration of a lupus anticoagulant and/or anticardiolipin antibody
What causes thrombocytopenia in the antiphospholipid syndrome?
increased peripheral platelet destruction due to vascular angiopathy and increased platelet consumption in the microvasculature
What is the function of fibrinogen?
functions as a bridging ligand for the the platelet receptor GP IIB/IIIA in the platelet-platelet matrix at sites of vascular damage
What is dysfibrinogenemia?
an abnormal fibrinogen protein
What are causes of Vitamin K deficiency?
• biliary tract disease that interferes with enterohepatic circulation & leads to decreased absorption of vitamin K • drugs (antibiotics, cephalosporins) • poor nutritional status
Patients with liver disease have low levels of nearly all factors except _____.
Factor VIII