2.4 Inhibitors, Thrombotic Disorders, and Anticoagulant Drugs Flashcards
Which characteristic describes antithrombin (AT)?
A. It is synthesized in megakaryocytes
B. It is activated by protein C
C. It is a cofactor of heparin
D. It is a pathological inhibitor of coagulation
C. It is a cofactor of heparin
Which laboratory test is affected by heparin therapy?
A. Thrombin time
B. Fibrinogen assay
C. Protein C assay
D. Protein S assay
A. Thrombin time
Abnormal APTT caused by a pathological circulating anticoagulant is:
A. Corrected with factor VIII–deficient plasma
B. Corrected with factor IX–deficient plasma
C. Corrected with normal plasma
D. Not corrected with normal plasma
D. Not corrected with normal plasma
The lupus anticoagulant affects which of the following tests?
A. Factor VIII assay
B. Factor IX assay
C. VWF assay
D. Phospholipid-dependent assays
D. Phospholipid-dependent assays
Which statement about warfarin (Coumadin) is accurate?
A. It is a vitamin B antagonist
B. It is not recommended for pregnant and lactating women
C. It needs AT as a cofactor
D. APTT test is used to monitor its dosage
B. It is not recommended for pregnant and lactating women
Which statement regarding protein C is correct?
A. It is a vitamin K–independent zymogen
B. It is activated by fibrinogen
C. It activates cofactors V and VIII
D. Its activity is enhanced by protein S
D. Its activity is enhanced by protein S
Which of the following is an appropriate screening test for the diagnosis of lupus anticoagulant?
A. Thrombin time
B. Diluted Russell viper venom test (DRVVT)
C. D-dimer test
D. Fibrinogen assay
B. Diluted Russell viper venom test (DRVVT)
Which of the following is most commonly associated with activated protein C resistance (APCR)?
A. Bleeding
B. Thrombosis
C. Epistaxis
D. Menorrhagia
B. Thrombosis
A 50-year-old man has been on heparin for the past 7 days. Which combination of tests is expected to be abnormal?
A. PT and APTT only
B. APTT, TT only
C. APTT, TT, fibrinogen assay
D. PT, APTT, TT
D. PT, APTT, TT
Which of the following drugs inhibits ADP-mediated PLT aggregation?
A. Heparin
B. Warfarin
C. Aspirin
D. Prasugrel
D. Prasugrel
Thrombin–TM complex is necessary for activation of:
A. Protein C
B. AT
C. Protein S
D. Factors V and VIII
A. Protein C
Which test is used to monitor heparin therapy?
A. INR
B. Chromogenic anti–factor Xa assay
C. TT
D. PT
B. Chromogenic anti–factor Xa assay
Which test is commonly used to monitor warfarin therapy?
A. INR
B. APTT
C. TT
D. Ecarin time
Which clotting factors (cofactors) are inhibited by protein S?
A. Factors V and X
B. Factors Va and VIIIa
C. Factors VIII and IX
D. Factors VIII and X
A. Factors V and X
Which drug promotes fibrinolysis?
A. Warfarin
B. Heparin
C. Urokinase
D. Aspirin
C. Urokinase
Diagnosis of lupus anticoagulant is confirmed by which of the following criteria?
A. Decreased APTT
B. Correction of APPT by mixing studies
C. Neutralization of the antibody by high concentration of phospholipids
D. Confirmation that abnormal coagulation tests are related to factor deficiencies
C. Neutralization of the antibody by high concentration of phospholipids
Which of the following abnormalities is consistent with the presence of lupus anticoagulant?
A. Decreased APTT/bleeding complications
B. Prolonged APTT/thrombosis
C. Prolonged APTT/thrombocytosis
D. Thrombocytosis/thrombosis
B. Prolonged APTT/thrombosis
Which of the following is a characteristic of LMWH?
A. Generally requires monitoring
B. Specifically acts on factor Va
C. Has a longer half-life compared with unfractionated heparin (UFH)
D. Can be used as a fibrinolytic agent
C. Has a longer half-life compared with unfractionated heparin (UFH)
Which of the following tests is most likely to be abnormal in patients taking aspirin?
A. PLT morphology
B. PLT count
C. PLT aggregation
D. PT
C. PLT aggregation
Which of the following is associated with AT deficiency?
A. Thrombocytosis
B. Thrombosis
C. Thrombocytopenia
D. Bleeding
B. Thrombosis
Which of the following may be associated with thrombotic events?
A. Decreased protein C
B. Increased fibrinolysis
C. Afibrinogenemia
D. Idiopathic thrombocytopenic purpura
A. Decreased protein C
Aspirin resistance may be associated with:
A. Bleeding
B. Factor VIII deficiency
C. Thrombosis
D. Thrombocytosis
C. Thrombosis
Prolonged TT is indicative of which of the following antithrombotic agents?
A. Prasugrel
B. Clopidogrel
C. Aspirin
D. Heparin
D. Heparin
Screening tests for thrombophilia should be performed on:
A. All pregnant women because of the risk of thrombosis
B. Patients with a negative family history
C. Patients with thrombotic events occurring at a young age
D. Patients who are receiving anticoagulant therapy
C. Patients with thrombotic events occurring at a young age
Prothrombin G20210A is characterized by which of the following causes and conditions?
A. Single mutation of prothrombin molecule/bleeding
B. Single mutation of prothrombin molecule/thrombosis
C. Decreased levels of prothrombin in plasma/thrombosis
D. Increased levels of prothrombin in plasma/bleeding
B. Single mutation of prothrombin molecule/thrombosis
Factor V Leiden promotes thrombosis by preventing:
A. Inactivation of factor Va
B. Activation of factor V
C. Activation of protein C
D. Activation of protein S
A. Inactivation of factor Va
What is the approximate incidence of antiphospholipid antibodies in the general population?
A. Less than 1%
B. 1%–2%
C. 3%–8%
D. 10%–15%
B. 1%–2%
Which of the following laboratory tests is helpful in the diagnosis of aspirin resistance?
A. APTT
B. PT
C. PLT count and morphology
D. PLT aggregation
D. PLT aggregation
Which of the following complications may occur as a result of decreased tissue factor pathway inhibitor (TFPI)?
A. Increased episodes of hemorrhage
B. Increased risk of thrombosis
C. Impaired PLT plug formation
D. Immune thrombocytopenia
B. Increased risk of thrombosis
Factor VIII inhibitors occur in __________ of patients with factor VIII deficiency.
A. 40%–50%
B. 30%–40%
C. 25%–30%
D. 20%–25%
D. 20%–25%
Which therapy and resulting mode of action are appropriate for the treatment of a patient with a high titer of factor VIII inhibitors?
A. Factor VIII concentrate to neutralize the antibodies
B. Recombinant factor VIIa (rVIIa) to activate factor X
C. Factor X concentrate to activate the common pathway
D. FFP to replace factor VIII
B. Recombinant factor VIIa (rVIIa) to activate factor X
The Bethesda assay is used for which determination?
A. Lupus anticoagulant titer
B. Factor VIII inhibitor titer
C. Factor V Leiden titer
D. Protein S deficiency
B. Factor VIII inhibitor titer
Hyperhomocysteinemia may be a risk factor for:
A. Bleeding
B. Thrombocythemia
C. Thrombosis
D. Thrombocytopenia
C. Thrombosis
Which drug may be associated with DVT?
A. Aspirin
B. tPA
C. Oral contraceptives
D. Clopidogrel (Plavix)
C. Oral contraceptives
Argatroban may be used as an anticoagulant drug in patients with:
A. DVT
B. Hemorrhage
C. TTP
D. Thrombocytosis
A. DVT
Heparin-induced thrombocytopenia (HIT) results from:
A. Antibodies to heparin
B. Antibodies to PLTs
C. Antibodies to PF4
D. Antibodies to heparin–PF4 complex
D. Antibodies to heparin–PF4 complex
Which laboratory test is used to screen for APCR?
A. Mixing studies with normal plasma
B. Mixing studies with factor-deficient plasma
C. Modified APTT with and without APC
D. Modified PT with and without APC
C. Modified APTT with and without APC
Ecarin clotting time may be used to monitor:
A. Heparin therapy
B. Warfarin therapy
C. Fibrinolytic therapy
D. Bivalirudin
D. Bivalirudin
Which of the following may interfere with the APCR screening test?
A. Lupus anticoagulant
B. Protein C deficiency
C. AT deficiency
D. Protein S deficiency
A. Lupus anticoagulant
Thrombophilia may be associated with which of the following disorders?
A. Afibrinogenemia
B. Hypofibrinogenemia
C. Factor VIII inhibitor
D. Hyperfibrinogenemia
D. Hyperfibrinogenemia
Which of the following anticoagulant drugs can be used in patients with HIT?
A. Warfarin
B. Heparin
C. Aspirin
D. Argatroban
D. Argatroban
Which of the following is the preferred method to monitor heparin therapy at the point of care during cardiac surgery?
A. APTT
B. ACT
C. PT
D. TT
B. ACT
Mrs. Smith has the following laboratory results and no history of bleeding:
APTT = prolonged
APTT results on a 1:1 mixture of the patient’s plasma with normal plasma:
Preincubation: prolonged APTT
2-hour incubation: prolonged APTT
These results are consistent with:
A. Factor VIII deficiency
B. Factor VIII inhibitor
C. Lupus anticoagulant
D. Protein C deficiency
C. Lupus anticoagulant
Which test may be used to monitor LMWH therapy?
A. APTT
B. INR
C. Anti–factor Xa heparin assay
D. ACT
C. Anti–factor Xa heparin assay