2.4 Inhibitors, Thrombotic Disorders, and Anticoagulant Drugs

Question 1

Which characteristic describes antithrombin (AT)?

Answer 1

It is a cofactor of heparin

Question 2

Which laboratory test is affected by heparin therapy?

Answer 2

Thrombin time

Question 3

Abnormal APTT caused by a pathological circulating anticoagulant is:

Answer 3

Not corrected with normal plasma

Question 4

The lupus anticoagulant affects which of the following tests?

Answer 4

Phospholipid-dependent assays

Question 5

Which statement about warfarin (Coumadin) is accurate?

Answer 5

It is not recommended for pregnant and lactating women

Question 6

Which statement regarding protein C is correct?

Answer 6

Its activity is enhanced by protein S

Question 7

Which of the following is an appropriate screening test for the diagnosis of lupus anticoagulant?

Answer 7

Diluted Russell viper venom test (DRVVT)

Question 8

Which of the following is most commonly associated with activated protein C resistance (APCR)?

Answer 8

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?

Answer 9

PT, APTT, TT

Question 10

Which of the following drugs inhibits ADP-mediated PLT aggregation?

Answer 10

Prasugrel

Question 11

Thrombin–TM complex is necessary for activation of:

Answer 11

Protein C

Question 12

Which test is used to monitor heparin therapy?

Answer 12

Chromogenic anti–factor Xa assay

Question 13

Which test is commonly used to monitor warfarin therapy?

Answer 13

INR

Question 14

Which clotting factors (cofactors) are inhibited by protein S?

Answer 14

Factors Va and VIIIa

Question 15

Which drug promotes fibrinolysis?

Answer 15

Urokinase

Question 16

Diagnosis of lupus anticoagulant is confirmed by which of the following criteria?

Answer 16

Neutralization of the antibody by high concentration of phospholipids

Question 17

Which of the following abnormalities is consistent with the presence of lupus anticoagulant?

Answer 17

Prolonged APTT/thrombosis

Question 18

Which of the following is a characteristic of LMWH?

Answer 18

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?

Answer 19

PLT aggregation

Question 20

Which of the following is associated with AT deficiency?

Answer 20

Thrombosis

Question 21

Which of the following may be associated with thrombotic events?

Answer 21

Decreased protein C

Question 22

Aspirin resistance may be associated with:

Answer 22

Thrombosis

Question 23

Prolonged TT is indicative of which of the following antithrombotic agents?

Answer 23

Heparin

Question 24

Screening tests for thrombophilia should be performed on:

Answer 24

Patients with thrombotic events occurring at a young age

Question 25

Prothrombin G20210A is characterized by which of the following causes and conditions?

Answer 25

Single mutation of prothrombin molecule/thrombosis

Question 26

Factor V Leiden promotes thrombosis by preventing:

Answer 26

Inactivation of factor Va

Question 27

What is the approximate incidence of antiphospholipid antibodies in the general population?

Answer 27

1%–2%

Question 28

Which of the following laboratory tests is helpful in the diagnosis of aspirin resistance?

Answer 28

PLT aggregation

Question 29

Which of the following complications may occur as a result of decreased tissue factor pathway inhibitor (TFPI)?

Answer 29

Increased risk of thrombosis

Question 30

Factor VIII inhibitors occur in __________ of patients with factor VIII deficiency.

Answer 30

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?

Answer 31

Recombinant factor VIIa (rVIIa) to activate factor X

Question 32

The Bethesda assay is used for which determination?

Answer 32

Factor VIII inhibitor titer

Question 33

Hyperhomocysteinemia may be a risk factor for:

Answer 33

Thrombosis

Question 34

Which drug may be associated with DVT?

Answer 34

Oral contraceptives

Question 35

Argatroban may be used as an anticoagulant drug in patients with:

Answer 35

DVT

Question 36

Heparin-induced thrombocytopenia (HIT) results from:

Answer 36

Antibodies to heparin–PF4 complex

Question 37

Which laboratory test is used to screen for APCR?

Answer 37

Modified APTT with and without APC

Question 38

Ecarin clotting time may be used to monitor:

Answer 38

Bivalirudin

Question 39

Which of the following may interfere with the APCR screening test?

Answer 39

Lupus anticoagulant

Question 40

Thrombophilia may be associated with which of the following disorders?

Answer 40

Hyperfibrinogenemia

Question 41

Which of the following anticoagulant drugs can be used in patients with HIT?

Answer 41

Argatroban

Question 42

Which of the following is the preferred method to monitor heparin therapy at the point of care during cardiac surgery?

Answer 42

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:

Answer 43

Lupus anticoagulant

Question 44

Which test may be used to monitor LMWH therapy?

Answer 44

Anti–factor Xa heparin assay