Podcast
Questions and Answers
What is a significant characteristic of disseminated intravascular coagulation (DIC)?
What is a significant characteristic of disseminated intravascular coagulation (DIC)?
Which laboratory test results would most likely indicate the presence of DIC?
Which laboratory test results would most likely indicate the presence of DIC?
Which statement regarding the D-dimer assay is accurate?
Which statement regarding the D-dimer assay is accurate?
What is the primary issue indicated by a prolonged partial thromboplastin time (PTT) in a patient?
What is the primary issue indicated by a prolonged partial thromboplastin time (PTT) in a patient?
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What role do FDP and D-dimer assays play in clinical diagnostics?
What role do FDP and D-dimer assays play in clinical diagnostics?
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What is the main purpose of the prothrombin time (PT) test?
What is the main purpose of the prothrombin time (PT) test?
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Which of the following coagulation tests is specifically used to assess the intrinsic pathway?
Which of the following coagulation tests is specifically used to assess the intrinsic pathway?
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When drawing blood for a coagulation assay, what type of tube is typically used?
When drawing blood for a coagulation assay, what type of tube is typically used?
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What does the international normalized ratio (INR) primarily measure?
What does the international normalized ratio (INR) primarily measure?
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What is the result of adding citrate to the blood sample during coagulation testing?
What is the result of adding citrate to the blood sample during coagulation testing?
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In which situation would you order a thrombin time (TT) test?
In which situation would you order a thrombin time (TT) test?
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Fibrin degradation products (FDP) assays are primarily used to assess which process?
Fibrin degradation products (FDP) assays are primarily used to assess which process?
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If a patient presents with unexplained bleeding, which two main factors should be evaluated?
If a patient presents with unexplained bleeding, which two main factors should be evaluated?
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What does the PT test primarily assess?
What does the PT test primarily assess?
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Why was the international normalized ratio (INR) developed?
Why was the international normalized ratio (INR) developed?
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What is the primary purpose of coagulation assays?
What is the primary purpose of coagulation assays?
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What is the primary purpose of the activated partial thromboplastin time (aPTT)?
What is the primary purpose of the activated partial thromboplastin time (aPTT)?
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Which vitamin K-dependent clotting factor has the shortest half-life?
Which vitamin K-dependent clotting factor has the shortest half-life?
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What is the normal range for the Prothrombin Time (PT)?
What is the normal range for the Prothrombin Time (PT)?
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Why are patients with advanced liver disease at high risk of bleeding?
Why are patients with advanced liver disease at high risk of bleeding?
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Which component is essential for the activation of the extrinsic coagulation pathway?
Which component is essential for the activation of the extrinsic coagulation pathway?
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What coagulation assays will be prolonged in patients with liver disease?
What coagulation assays will be prolonged in patients with liver disease?
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How does the aPTT differ from the PTT?
How does the aPTT differ from the PTT?
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Which assay is used to monitor warfarin therapy?
Which assay is used to monitor warfarin therapy?
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What does the thrombin time (TT) primarily assess?
What does the thrombin time (TT) primarily assess?
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What is the normal range for the activated partial thromboplastin time (aPTT)?
What is the normal range for the activated partial thromboplastin time (aPTT)?
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What laboratory value is primarily monitored for heparin therapy?
What laboratory value is primarily monitored for heparin therapy?
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What does an elevated FDP assay indicate?
What does an elevated FDP assay indicate?
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How does heparin function in relation to antithrombin?
How does heparin function in relation to antithrombin?
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Study Notes
Coagulation Testing
- Coagulation testing helps evaluate how well a patient can form fibrin.
- Coagulation tests can evaluate patients with unexplained bleeding or monitor anticoagulant therapy.
- Common coagulation tests include prothrombin time (PT), international normalized ratio (INR), partial thromboplastin time (PTT), and thrombin time (TT).
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PT assesses the extrinsic and common pathways of the coagulation cascade.
- Normal range: 11-14 seconds.
- PT values can vary between hospitals due to different thromboplastin reagents.
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INR standardizes PT values.
- Normal range: 0.8-1.2.
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PTT assesses the intrinsic and common pathways of the coagulation cascade.
- Normal range: 25-35 seconds.
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aPTT is similar to PTT but includes an activator that speeds up clot formation.
- More sensitive than PTT and used to monitor heparin therapy.
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TT assesses the conversion of fibrinogen to fibrin.
- Normal range: 12-14 seconds.
Monitoring Anticoagulants
- INR is used to monitor warfarin therapy, which acts as a vitamin K antagonist.
- PTT is used to monitor unfractionated heparin therapy, which indirectly binds to antithrombin to inactivate clotting factors.
Fibrin Degradation Products (FDP)
- FDP assay measures the amount of fibrin degradation products present.
- Elevated FDPs indicate fibrinolysis (breaking down of clots) in the body.
- D-dimer assay measures only crosslinked fibrin in clots, making it more specific than FDP assay.
- FDP and D-dimer assays are useful for evaluating disorders with increased clotting and breakdown like DVT, PE, and DIC.
Disseminated Intravascular Coagulation (DIC)
- DIC is a disorder with abnormal activation of the coagulation cascade leading to widespread microthrombi.
- DIC consumes clotting factors, fibrin, and platelets resulting in hemorrhage, thrombocytopenia, factor deficiencies, and vessel injuries.
- Coagulation studies supporting DIC include prolonged PT, PTT, and TT; elevated FDP or D-dimer assay; and decreased platelet count.
Mixing Study
- A mixing study can help determine if a prolonged PTT is due to a factor deficiency or an inhibitor (antiphospholipid antibody).
- The study involves mixing the patient's plasma with normal plasma.
- If the PTT corrects after mixing, the prolonged PTT is likely due to a factor deficiency.
- If the PTT does not correct, the prolonged PTT is likely due to an inhibitor.
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Description
This quiz covers essential concepts of coagulation testing, including the significance of various tests like PT, INR, PTT, and TT. Understand how these tests help evaluate bleeding disorders and monitor anticoagulant therapy. Test your knowledge on normal ranges and the clinical implications of these assessments.
