2.4 Inhibitors, Thrombotic Disorders, and Anticoagulant Drugs

Question 1

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

Answer 1

C. It is a cofactor of heparin

Question 2

Which laboratory test is affected by heparin therapy?
A. Thrombin time
B. Fibrinogen assay
C. Protein C assay
D. Protein S assay

Answer 2

A. Thrombin time

Question 3

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

Answer 3

D. Not corrected with normal plasma

Question 4

The lupus anticoagulant affects which of the following tests?
A. Factor VIII assay
B. Factor IX assay
C. VWF assay
D. Phospholipid-dependent assays

Answer 4

D. Phospholipid-dependent assays

Question 5

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

Answer 5

B. It is not recommended for pregnant and lactating women

Question 6

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

Answer 6

D. Its activity is enhanced by protein S

Question 7

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

Answer 7

B. Diluted Russell viper venom test (DRVVT)

Question 8

Which of the following is most commonly associated with activated protein C resistance (APCR)?
A. Bleeding
B. Thrombosis
C. Epistaxis
D. Menorrhagia

Answer 8

B. Thrombosis

Question 9

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

Answer 9

D. PT, APTT, TT

Question 10

Which of the following drugs inhibits ADP-mediated PLT aggregation?
A. Heparin
B. Warfarin
C. Aspirin
D. Prasugrel

Answer 10

D. Prasugrel

Question 11

Thrombin–TM complex is necessary for activation of:
A. Protein C
B. AT
C. Protein S
D. Factors V and VIII

Answer 11

A. Protein C

Question 12

Which test is used to monitor heparin therapy?
A. INR
B. Chromogenic anti–factor Xa assay
C. TT
D. PT

Answer 12

B. Chromogenic anti–factor Xa assay

Question 13

Which test is commonly used to monitor warfarin therapy?
A. INR
B. APTT
C. TT
D. Ecarin time

Question 14

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

Answer 14

A. Factors V and X

Question 15

Which drug promotes fibrinolysis?
A. Warfarin
B. Heparin
C. Urokinase
D. Aspirin

Answer 15

C. Urokinase

Question 16

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

Answer 16

C. Neutralization of the antibody by high concentration of phospholipids

Question 17

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

Answer 17

B. Prolonged APTT/thrombosis

Question 18

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

Answer 18

C. Has a longer half-life compared with unfractionated heparin (UFH)

Question 19

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

Answer 19

C. PLT aggregation

Question 20

Which of the following is associated with AT deficiency?
A. Thrombocytosis
B. Thrombosis
C. Thrombocytopenia
D. Bleeding

Answer 20

B. Thrombosis

Question 21

Which of the following may be associated with thrombotic events?
A. Decreased protein C
B. Increased fibrinolysis
C. Afibrinogenemia
D. Idiopathic thrombocytopenic purpura

Answer 21

A. Decreased protein C

Question 22

Aspirin resistance may be associated with:
A. Bleeding
B. Factor VIII deficiency
C. Thrombosis
D. Thrombocytosis

Answer 22

C. Thrombosis

Question 23

Prolonged TT is indicative of which of the following antithrombotic agents?
A. Prasugrel
B. Clopidogrel
C. Aspirin
D. Heparin

Answer 23

D. Heparin

Question 24

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

Answer 24

C. Patients with thrombotic events occurring at a young age

Question 25

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

Answer 25

B. Single mutation of prothrombin molecule/thrombosis

Question 26

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

Answer 26

A. Inactivation of factor Va

Question 27

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%

Answer 27

B. 1%–2%

Question 28

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

Answer 28

D. PLT aggregation

Question 29

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

Answer 29

B. Increased risk of thrombosis

Question 30

Factor VIII inhibitors occur in __________ of patients with factor VIII deficiency. A. 40%–50% B. 30%–40% C. 25%–30% D. 20%–25%

Answer 30

D. 20%–25%

Question 31

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

Answer 31

B. Recombinant factor VIIa (rVIIa) to activate factor X

Question 32

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

Answer 32

B. Factor VIII inhibitor titer

Question 33

Hyperhomocysteinemia may be a risk factor for: A. Bleeding B. Thrombocythemia C. Thrombosis D. Thrombocytopenia

Answer 33

C. Thrombosis

Question 34

Which drug may be associated with DVT? A. Aspirin B. tPA C. Oral contraceptives D. Clopidogrel (Plavix)

Answer 34

C. Oral contraceptives

Question 35

Argatroban may be used as an anticoagulant drug in patients with: A. DVT B. Hemorrhage C. TTP D. Thrombocytosis

Answer 35

A. DVT

Question 36

Heparin-induced thrombocytopenia (HIT) results from: A. Antibodies to heparin B. Antibodies to PLTs C. Antibodies to PF4 D. Antibodies to heparin–PF4 complex

Answer 36

D. Antibodies to heparin–PF4 complex

Question 37

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

Answer 37

C. Modified APTT with and without APC

Question 38

Ecarin clotting time may be used to monitor: A. Heparin therapy B. Warfarin therapy C. Fibrinolytic therapy D. Bivalirudin

Answer 38

D. Bivalirudin

Question 39

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

Answer 39

A. Lupus anticoagulant

Question 40

Thrombophilia may be associated with which of the following disorders? A. Afibrinogenemia B. Hypofibrinogenemia C. Factor VIII inhibitor D. Hyperfibrinogenemia

Answer 40

D. Hyperfibrinogenemia

Question 41

Which of the following anticoagulant drugs can be used in patients with HIT? A. Warfarin B. Heparin C. Aspirin D. Argatroban

Answer 41

D. Argatroban

Question 42

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

Answer 42

B. ACT

Question 43

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

Answer 43

C. Lupus anticoagulant

Question 44

Which test may be used to monitor LMWH therapy? A. APTT B. INR C. Anti–factor Xa heparin assay D. ACT

Answer 44

C. Anti–factor Xa heparin assay