Hematology 2: Coagulation Tests Part 2 (Desmopressin) - Week 10
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Questions and Answers

What is the role of activated protein C in the clotting assay described?

  • Activates factor V and factor VIII
  • Has no impact on factor V and factor VIII
  • Inhibits factor V and factor VIII (correct)
  • Enhances factor V and factor VIII activity

    • How is the clotting time related to the percentage of protein C activity in the plasma dilution?

  • Directly proportional
  • Inversely proportional (correct)
  • Not related
  • Randomly associated

    • In the protein S antigen assay, what occurs when anti-protein S peroxidase conjugate is added?

  • Activates protein S antigen
  • Forms a sandwich with the free antigenic determinants of protein S (correct)
  • It inhibits the binding process
  • Removes protein S antigen from the solution

    • What is the effect of protein C activation in the presence of Protein C activator?

    <p>Prolongs aPTT</p> Signup and view all the answers

    What binds to the free antigenic determinants of protein S during the assay?

    <p>Anti-protein S antibody</p> Signup and view all the answers

    How does the presence of activated protein C impact factor V and factor VIII?

    <p>Inhibits factor V and factor VIII</p> Signup and view all the answers

    What is released from the substrate when a substrate is added to a plasma streptokinase mixture?

    <p>Paranitroanilide (pNA)</p> Signup and view all the answers

    What forms a plasminogen-streptokinase complex in the plasma specimen?

    <p>Plasminogen</p> Signup and view all the answers

    How is the release of paranitroanilide (pNA) measured?

    <p>Spectrophotometrically</p> Signup and view all the answers

    What is the value of the pNA product directly proportional to?

    <p>The amount of plasminogen</p> Signup and view all the answers

    What catalyzes the release of paranitroanilide (pNA) from the substrate in the protein C chromogenic method?

    <p>Activated protein C</p> Signup and view all the answers

    What reagent is typically added to stop the reaction in clotting time activity assays?

    <p>20% acetic acid</p> Signup and view all the answers

    What is the purpose of the Protamine Sulfate Dilution Test?

    <p>To detect the presence of fibrin monomers or fibrin degradation products (FDPs)</p> Signup and view all the answers

    What is the principle behind the Ethanol Gelation Test?

    <p>Fibrin soluble monomers dissociate in the presence of 50% ethanol solution, resulting in their polymerization and gel formation</p> Signup and view all the answers

    Which of the following is a specific evidence of intravascular fibrin formation?

    <p>Positive result in the Latex D-Dimer Assay</p> Signup and view all the answers

    In the laboratory profile of disseminated intravascular coagulation (DIC), which of the following is typically observed?

    <p>Low level of fibrinogen</p> Signup and view all the answers

    Which of the following conditions is associated with a decreased level of plasminogen?

    <p>Thrombolytic therapy</p> Signup and view all the answers

    Which of the following assays is based on the principle of agglutination of latex particles coated with antibodies against fibrin or fibrinogen fragments?

    <p>Latex Fibrin Degradation Product (FDP) Assay</p> Signup and view all the answers

    What is the role of the enzyme peroxidase in the assay for Protein S?

    <p>It catalyzes the color change reaction with OPD, which is proportional to the concentration of Protein S.</p> Signup and view all the answers

    What percentage of total Protein S antigen in plasma is normally bound to C4b binding protein (C4b BP)?

    <p>60%</p> Signup and view all the answers

    What is the role of free Protein S in the coagulation process?

    <p>It acts as a cofactor for the anticoagulant effects of activated Protein C.</p> Signup and view all the answers

    How is the Protein S bound to C4b BP removed from plasma in the assay?

    <p>By precipitation with polyethylene glycol</p> Signup and view all the answers

    Which of the following conditions is NOT associated with an acquired deficiency of Protein S?

    <p>Hemophilia</p> Signup and view all the answers

    What principle is used in the Protein S clotting assay to determine the percentage of functional Protein S?

    <p>The clotting time is inversely proportional to the percentage of Protein S activity.</p> Signup and view all the answers

    Study Notes

    Protein C Clotting Assay

    • Diluted plasma is incubated with protein C deficient plasma in the presence of protein C activator (Agkistrodon contortrix)
    • The amount of protein C in plasma is related to the degree of correction obtained
    • Activated protein C inhibits factor V and factor VIII (labile factors), causing prolongation of aPTT
    • Clotting time obtained for each plasma dilution is inversely proportional to the percentage of protein C activity

    Protein S Assay

    • Plasma dilutions containing protein S antigen are incubated in microwells coated with anti-protein S antibody
    • Anti-protein S peroxidase conjugate is added, binding to free antigenic determinants
    • Plasminogen present in the plasma specimen forms a plasminogen-streptokinase complex, which possesses plasmin-like activity
    • When a substrate is added, this plasmin-like activity releases pNA, which is measured spectrophotometrically
    • The value of this product is directly proportional to the amount of plasminogen present in the plasma

    Protein C Chromogenic Method

    • Plasma is incubated with protein C activator (lyophilized powder from Agkistrodon contortrix venom)
    • Upon addition of the substrate, activated protein C catalyzes the release of pNA from the substrate
    • This is measured spectrophotometrically and is directly proportional to the concentration of protein C in the plasma

    Disorders and Tests

    • Disseminated Intravascular Coagulation (DIC)
      • Laboratory profile:
        • Platelet count
        • Protime
        • D-dimer
        • Fibrinogen
    • Tests for DIC:
      • Protamine Sulfate Dilution Test
      • Ethanol Gelation Test
      • Latex Fibrin Degradation Product (FDP) Assay
      • Latex D-Dimer Assay
    • Plasminogen assay
      • Measured by electro immunoassay and radioimmunoassay (RIA)
      • Functional assays include fibrin plate and chromogenic assays

    Protein S

    • Free protein S component is a cofactor for the anticoagulant effects of activated protein C
    • Protein S bound to C4b BP is removed from the plasma by precipitating with polyethylene glycol
    • Acquired deficiencies of protein S:
      • Using oral contraceptives
      • Pregnancies
      • Intake of oral anticoagulants
      • DIC
      • Liver disease
      • Diabetes type I

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    Description

    This quiz covers coagulation tests related to desmopressin, including Protamine Sulfate Dilution Test and Laboratory Profile of Disseminated Intravascular Coagulation (DIC). Test your knowledge on detecting fibrin monomers, FDPs, platelet count, and more in the context of hematology.

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