NAPLEX Practice Questions

NCLEX Focus Exploring Anticoagulant Therapy, aPTT
Test for DIC

Question 11

A patient with a history of chronic stable angina is undergoing elective hip replacement surgery and is prescribed enoxaparin for venous thromboembolism (VTE) prophylaxis. The patient’s current medications include aspirin 81 mg daily and atorvastatin. Which of the following is an important consideration for managing this patient’s medication regimen?

A. Discontinue aspirin 7 days prior to surgery to reduce the risk of bleeding.
B. Increase the dose of atorvastatin to reduce the risk of post-operative thrombosis.
C. Administer enoxaparin 12 hours before surgery for optimal VTE prophylaxis.
D. Continue aspirin therapy through the perioperative period to protect against myocardial infarction.
E. Substitute enoxaparin with a direct oral anticoagulant (DOAC) immediately before surgery.

Rationale: In patients with a history of coronary artery disease, continuing low-dose aspirin therapy through the perioperative period is often recommended to reduce the risk of myocardial infarction, balancing the slightly increased risk of bleeding with the significant benefit of preventing cardiac events. The timing of enoxaparin administration relative to surgery requires careful consideration to minimize bleeding risk, but discontinuing aspirin is not generally advised for these patients without a compelling reason. Increasing the dose of atorvastatin preoperatively has no direct effect on post-operative thrombosis prevention in this context, and substituting enoxaparin with a DOAC immediately before surgery does not align with standard VTE prophylaxis protocols in the perioperative setting.

Question 12

A patient on long-term warfarin therapy for atrial fibrillation requires a dental extraction. The patient’s INR is currently within the therapeutic range. Which of the following is the most appropriate management strategy to minimize the risk of bleeding associated with the dental procedure?

A. Discontinue warfarin 5 days before the dental extraction.
B. Administer oral vitamin K 1 day before the procedure.
C. Maintain warfarin therapy without adjustment.
D. Bridge with low-molecular-weight heparin (LMWH) before and after the procedure.
E. Switch to a direct oral anticoagulant (DOAC) temporarily before the procedure.

Rationale: For minor dental procedures, including extractions, it is often safe to continue warfarin therapy without adjustment, provided the INR is within the therapeutic range. This strategy minimizes the risk of thromboembolism without significantly increasing the risk of bleeding. Discontinuing warfarin, administering vitamin K, bridging with LMWH, or switching to a DOAC are strategies that might be considered for more invasive procedures or in situations where bleeding risk is higher, but they are generally not necessary for dental extractions.

Question 13

A 62-year-old woman with a recent history of acute venous thromboembolism (VTE) is started on rivaroxaban. She expresses concern about the risk of bleeding. Which of the following is an important dietary counseling point for this patient?

A. Limit intake of green leafy vegetables.
B. Avoid grapefruit and grapefruit juice.
C. Increase intake of vitamin K-rich foods.
D. Maintain a consistent intake of foods rich in vitamin E.
E. Dietary habits do not significantly affect rivaroxaban’s efficacy or safety.

Rationale: Unlike warfarin, which requires patients to maintain a consistent intake of vitamin K-rich foods, rivaroxaban’s anticoagulant effect is not significantly affected by dietary vitamin K. Therefore, patients do not need to limit intake of green leafy vegetables or adjust their diet for vitamin K or E. Grapefruit does not have a significant interaction with rivaroxaban, making it distinct from some other medications where grapefruit intake is a concern.

Question 14

A 75-year-old male with venous thromboembolism (VTE) is being treated with warfarin. He has a mechanical heart valve. The patient’s diet is high in vitamin K. Which of the following is a likely consequence of this diet?

A. Increased risk of thrombosis
B. Decreased warfarin dose requirements
C. Increased warfarin dose requirements
D. No impact on warfarin therapy
E. Increased risk of major bleeding

Rationale: A diet high in vitamin K can antagonize the effect of warfarin, potentially necessitating an increase in the warfarin dose to maintain therapeutic anticoagulation levels and achieve a therapeutic INR. Vitamin K acts as a co-factor for the synthesis of clotting factors, which warfarin inhibits by interfering with vitamin K recycling. Therefore, a higher dietary intake of vitamin K can reduce the efficacy of warfarin, leading to an increased dose requirement to maintain the desired anticoagulant effect. This management approach aims to prevent both thrombosis and bleeding risks associated with mechanical heart valves and VTE, respectively.

Question 15

A patient with a history of recurrent venous thromboembolism (VTE) is currently taking rivaroxaban. The patient is scheduled for major orthopedic surgery. Which of the following is the most appropriate management of rivaroxaban in this scenario?

A. Continue rivaroxaban without any changes.
B. Discontinue rivaroxaban 24 hours before surgery.
C. Discontinue rivaroxaban 5 days before surgery.
D. Switch to warfarin one week before surgery.
E. Initiate low-molecular-weight heparin (LMWH) as a bridge until the day of surgery.

Rationale: The pharmacokinetics of rivaroxaban allow for relatively short discontinuation times before surgical procedures to minimize the risk of bleeding. For major surgery, discontinuing rivaroxaban at least 24 hours before the procedure is generally recommended to ensure the anticoagulant effect has diminished. This strategy balances the need to reduce the risk of perioperative bleeding with the need to minimize the time without anticoagulation to prevent VTE. Switching to warfarin or initiating LMWH as a bridge therapy is unnecessary in this context and could complicate perioperative anticoagulation management.

Question 16

A patient taking dabigatran for stroke prevention in non-valvular atrial fibrillation presents with acute renal failure. The patient’s creatinine clearance is now estimated at 15 mL/min. Which of the following actions is most appropriate?

A. Continue dabigatran at the current dose.
B. Switch to warfarin therapy.
C. Temporarily discontinue dabigatran until renal function improves.
D. Reduce the dose of dabigatran.
E. Switch to a low-dose direct oral anticoagulant (DOAC) of a different class.

Rationale: In patients with significant renal impairment (creatinine clearance <30 mL/min), dabigatran, which is primarily excreted by the kidneys, may accumulate and increase the risk of bleeding. Switching to warfarin allows for anticoagulation with more predictable pharmacokinetics in the context of renal failure and enables INR monitoring to adjust the dose as needed. Temporary discontinuation of anticoagulation in patients with atrial fibrillation significantly increases the risk of stroke and is not recommended without a compelling indication. Reducing the dose of dabigatran or switching to a low-dose DOAC of a different class may not provide adequate stroke prevention in the context of severe renal impairment.

Question 17

Which of the following best describes the mechanism of action of direct oral anticoagulants (DOACs) like rivaroxaban and apixaban?

A. Inhibition of vitamin K-dependent clotting factors synthesis.
B. Direct inhibition of thrombin.
C. Direct inhibition of factor Xa.
D. Activation of antithrombin III.
E. Inhibition of platelet aggregation.

Rationale: DOACs such as rivaroxaban and apixaban work by directly inhibiting factor Xa, an essential enzyme in the coagulation cascade that converts prothrombin to thrombin. This mechanism of action is distinct from that of warfarin, which inhibits the synthesis of vitamin K-dependent clotting factors, and from direct thrombin inhibitors like dabigatran, which inhibit thrombin directly. DOACs do not activate antithrombin III nor directly inhibit platelet aggregation as their primary mechanism of action.

Question 18

A patient on apixaban therapy for atrial fibrillation develops a gastrointestinal bleed. Which of the following factors should be considered critical in the management of this patient?

A. Immediate initiation of vitamin K administration.
B. Use of tranexamic acid as a first-line treatment.
C. Assessment of apixaban plasma levels to guide therapy.
D. Potential use of andexanet alfa for reversal of anticoagulation.
E. Immediate switch to a direct thrombin inhibitor.

Rationale: In the event of a life-threatening bleed in a patient taking apixaban, andexanet alfa is a specific reversal agent that can be used to neutralize the anticoagulant effect of factor Xa inhibitors. Vitamin K is not effective for the reversal of apixaban and other direct oral anticoagulants. Tranexamic acid may be used to manage bleeding, but it does not reverse the anticoagulant effect of apixaban. Measuring apixaban plasma levels is not typically part of the acute management strategy for a bleed and does not directly guide reversal therapy. Switching to a direct thrombin inhibitor does not address the immediate need to reverse the anticoagulant effect and manage the bleed.

Question 19

A 58-year-old patient with a history of renal insufficiency and atrial fibrillation is on warfarin therapy. The patient’s latest blood work shows an INR of 3.8. The patient reports no signs of bleeding. Which of the following is the most appropriate next step in management?

A. Hold the next warfarin dose and reduce subsequent doses.
B. Administer oral vitamin K.
C. Continue warfarin at the current dose and recheck INR in 1 week.
D. Increase the warfarin dose to achieve a higher INR target.
E. Initiate bridging with low-molecular-weight heparin (LMWH).

Rationale: In patients with an INR slightly above the therapeutic range but without bleeding, the appropriate initial management often involves holding the next dose of warfarin and reducing subsequent doses to bring the INR back into the therapeutic range. Administering oral vitamin K is generally reserved for higher INR values or in the presence of bleeding. Continuing warfarin at the current dose without adjustment risks further INR elevation, while increasing the dose is contraindicated due to the already elevated INR. Bridging with LMWH is unnecessary in this scenario.

Question 20

For patients undergoing hip or knee replacement surgery, which of the following anticoagulants is NOT typically used for venous thromboembolism (VTE) prophylaxis?

A. Enoxaparin
B. Rivaroxaban
C. Dabigatran
D. Warfarin
E. Clopidogrel

Rationale: Clopidogrel, an antiplatelet agent, is not typically used for VTE prophylaxis in the context of hip or knee replacement surgery. Enoxaparin, rivaroxaban, dabigatran, and warfarin are all anticoagulants that have been used for VTE prophylaxis in this setting. Clopidogrel’s mechanism of action involves the inhibition of platelet aggregation, which is different from the mechanisms that prevent venous thromboembolism.

Question 21

A patient presents with a confirmed pulmonary embolism (PE) and is hemodynamically stable. The patient has no history of renal impairment. Which of the following treatment options is appropriate for initiating anticoagulation therapy?

A. Intravenous unfractionated heparin
B. Oral aspirin
C. Subcutaneous fondaparinux
D. Oral clopidogrel
E. Intravenous alteplase

Rationale: Subcutaneous fondaparinux is an appropriate option for initiating anticoagulation therapy in patients with a confirmed pulmonary embolism who are hemodynamically stable and without renal impairment. Intravenous unfractionated heparin is another option but requires more monitoring. Aspirin and clopidogrel are antiplatelet agents and not the first-line treatment for PE. Alteplase, a thrombolytic agent, is reserved for patients with PE who are hemodynamically unstable.

Question 22

A patient on apixaban for stroke prevention in atrial fibrillation requires urgent surgery. There is no time to wait for the drug’s effects to wear off naturally. Which of the following strategies is recommended to manage the risk of bleeding during surgery?

A. Administration of oral vitamin K
B. Use of protamine sulfate
C. Use of andexanet alfa
D. Immediate initiation of fresh frozen plasma
E. Switching to dabigatran before surgery

Rationale: Andexanet alfa is a specific reversal agent for the anticoagulant effects of factor Xa inhibitors like apixaban, making it the recommended strategy when urgent reversal is needed before surgery. Vitamin K and protamine sulfate are not effective in reversing the effects of apixaban. Fresh frozen plasma is not a direct reversal agent for DOACs and may not be effective in this scenario. Switching to another anticoagulant such as dabigatran does not address the urgent need to reverse anticoagulation before surgery.

Question 23

A patient with a mechanical heart valve is on anticoagulation therapy. Which of the following anticoagulants is considered the standard of care for this condition?

A. Dabigatran
B. Rivaroxaban
C. Warfarin
D. Apixaban
E. Edoxaban

Rationale: Warfarin is the standard of care for patients with mechanical heart valves requiring anticoagulation. Its efficacy and safety in this population have been well established, whereas the use of direct oral anticoagulants (DOACs) such as dabigatran, rivaroxaban, apixaban, and edoxaban is not recommended for patients with mechanical heart valves due to an increased risk of thromboembolic and bleeding events.

Question 24

Which of the following is a potential side effect unique to heparin therapy that requires monitoring?

A. Heparin-induced thrombocytopenia (HIT)
B. Hyperkalemia
C. Hypocalcemia
D. Gingival hyperplasia
E. Osteoporosis

Rationale: Heparin-induced thrombocytopenia (HIT) is a serious and unique side effect of heparin therapy that results in a significant reduction in platelet counts and an increased risk of thrombosis. It requires careful monitoring of platelet counts during heparin therapy. Hyperkalemia, hypocalcemia, gingival hyperplasia, and osteoporosis are not specifically associated with heparin therapy.

Question 25

A patient with non-valvular atrial fibrillation and a CHA2DS2-VASc score of 2 is being considered for anticoagulation therapy. Which of the following statements is true regarding the choice of anticoagulant?

A. Warfarin is the only option for patients with a CHA2DS2-VASc score of 2.
B. Direct oral anticoagulants (DOACs) are preferred over warfarin if there are no contraindications.
C. Antiplatelet therapy alone is sufficient for stroke prevention in this patient.
D. Intravenous unfractionated heparin should be used as long-term therapy.
E. No anticoagulation is needed for a CHA2DS2-VASc score of 2.

Rationale: For patients with non-valvular atrial fibrillation and a CHA2DS2-VASc score of 2, direct oral anticoagulants (DOACs) such as dabigatran, rivaroxaban, apixaban, and edoxaban are generally preferred over warfarin due to their favorable risk-benefit profile, ease of use, and the absence of the need for routine blood monitoring. Antiplatelet therapy alone is not sufficient for stroke prevention in these patients. Intravenous unfractionated heparin is not used for long-term therapy in this context. Anticoagulation is recommended for a CHA2DS2-VASc score of 2 to reduce the risk of stroke.

Question 26

A patient on warfarin therapy for atrial fibrillation reports consuming a large amount of green leafy vegetables daily. What is the most likely effect of this dietary habit on warfarin therapy?

A. Increased risk of thrombosis
B. Decreased risk of bleeding
C. No impact on warfarin therapy
D. Increased warfarin dose requirements
E. Decreased INR values

Rationale: Consuming a large amount of green leafy vegetables, which are high in vitamin K, can antagonize the effects of warfarin and may necessitate an increase in the warfarin dose to maintain therapeutic anticoagulation levels. Vitamin K is a cofactor for the synthesis of clotting factors, and warfarin works by inhibiting the recycling of vitamin K. Therefore, a high intake of vitamin K can decrease the effectiveness of warfarin, leading to increased dose requirements and potentially decreased INR values, which could increase the risk of thrombosis if not appropriately managed.

Question 27

Which of the following laboratory tests is most appropriate for monitoring the anticoagulant effect of dabigatran?

A. Prothrombin time (PT)
B. Activated partial thromboplastin time (aPTT)
C. Thrombin time (TT)
D. Platelet count
E. Anti-Xa assay

Rationale: Thrombin time (TT) is the most sensitive laboratory test for monitoring the anticoagulant effect of dabigatran, a direct thrombin inhibitor. While aPTT can provide some indication of dabigatran’s effect, it is not as sensitive or specific as TT. PT and anti-Xa assay are not appropriate for monitoring dabigatran’s effect, and platelet count does not reflect anticoagulation status.

Question 28

A patient is receiving enoxaparin for the treatment of deep vein thrombosis (DVT). The patient develops a rash and thrombocytopenia. Which of the following is the most likely diagnosis?

A. Heparin-induced thrombocytopenia (HIT)
B. Allergic reaction to enoxaparin
C. Vitamin K deficiency
D. Disseminated intravascular coagulation (DIC)
E. Enoxaparin overdose

Rationale: Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder that can occur in response to heparin therapy, including therapy with low-molecular-weight heparins like enoxaparin. HIT is characterized by a significant drop in platelet count and, potentially, new thromboses, rather than an allergic reaction or overdose symptoms. Vitamin K deficiency and disseminated intravascular coagulation (DIC) are not directly related to enoxaparin therapy and present with different clinical pictures.

Question 29

A patient with atrial fibrillation is being transitioned from rivaroxaban to warfarin due to insurance coverage changes. Which of the following strategies is appropriate for this transition?

A. Discontinue rivaroxaban and start warfarin the following day.
B. Overlap rivaroxaban and warfarin until the INR is therapeutic.
C. Use a bridging therapy with low-molecular-weight heparin during the transition.
D. Immediately switch to warfarin without overlapping, monitoring INR daily.
E. Initiate warfarin with a loading dose while continuing rivaroxaban for 5 days.

Rationale: When transitioning from rivaroxaban to warfarin, it is important to overlap the two medications until the INR reaches the therapeutic range for warfarin. This approach ensures continuous anticoagulation coverage during the transition period. Rivaroxaban has a relatively short half-life, so simply discontinuing it before starting warfarin could leave the patient at risk for thromboembolic events until the warfarin reaches therapeutic levels. Bridging with low-molecular-weight heparin is not typically necessary when transitioning from a direct oral anticoagulant like rivaroxaban to warfarin.

Question 30

For a patient with a history of heparin-induced thrombocytopenia (HIT) who requires anticoagulation, which of the following is an appropriate choice?

A. Unfractionated heparin
B. Low-molecular-weight heparin (LMWH)
C. Fondaparinux
D. Warfarin, initiated without overlap with heparin
E. Dabigatran, started immediately after discontinuing heparin

Rationale: Fondaparinux is a synthetic pentasaccharide that indirectly inhibits factor Xa. It does not cause heparin-induced thrombocytopenia (HIT) and is considered safe for use in patients with a history of HIT. Unfractionated heparin and low-molecular-weight heparin (LMWH) are contraindicated in patients with a history of HIT due to the risk of cross-reactivity and recurrence of HIT. Warfarin should not be initiated as monotherapy in the acute management of HIT due to the risk of venous limb gangrene, especially without bridging anticoagulation that does not carry a risk of HIT. Dabigatran is a direct thrombin inhibitor and could be considered in some cases, but fondaparinux is specifically recommended for initial anticoagulation in patients with a history of HIT.