Deck 35: Thrombophilia

Question 1

It has been determined that a patient has activated protein C resistance. Name the most prevalent genetic mutation associated with this finding.

A) Guanine to adenine substitution on nucleotide 20210 of the prothrombin gene
B) Lysine to glutamic acid substitution on the sixth position on the beta globin chain
C) Arginine to glutamine substitution at the 506 position of factor V protein
D) Translocation of chromosome 22 onto the long arm of chromosome 9

Answer 1

Arginine to glutamine substitution at the 506 position of factor V protein

Question 2

Failure of protein C to destroy FVa and FVIIIa results in an increase in what hemostatic system alteration?

A) Platelets
B) Production of thrombin
C) FVIII
D) FXa

Answer 2

Production of thrombin

Question 3

When is routine monitoring of LMWH indicated?

A) Obesity
B) Pediatric patients
C) Renal insufficiency
D) All of the above

Answer 3

All of the above

Question 4

A patient has been diagnosed with a coagulopathy and has been given Coumadin as a mode of treatment. What screening test(s) should be performed to monitor this treatment, and what effect will this therapy have on the coagulation pathway?

A) APTT; initial decrease in the vitamin K-dependent factors of the intrinsic pathway
B) PT-INR; initial decrease in the vitamin K-dependent factors of the extrinsic pathway
C) PT-INR and APTT; initial decrease in the vitamin K-dependent factors of all pathways
D) PT-INR; initial decrease in all vitamin K-dependent serine proteases

Question 5

Antithrombin and heparin cofactor II primarily inhibit which of the following factors?

A) FV, FVIII, and thrombin
B) FIXa, FXa, and thrombin
C) FXII and thrombin
D) Fibrinogen and thrombin

Question 6

Which of the following test results would help differentiate between type I and II protein C deficiencies?

A) PT and APTT
B) Protein C antigen assay
C) Protein C functional activity assay
D) Protein S assay

Question 7

A tendency to favor thrombus formation produced from an imbalance in the major constituents of the hemostatic system is defined as:

A) Hypercoagulability
B) Thrombophilia
C) Thrombosis
D) Thromboembolism

Question 8

During coumadin-induced anticoagulation, which factor's activity disappears most rapidly?

A) FIX
B) FVII
C) FVIII
D) FV

Question 9

Which of the following is thought to be a traditional risk factor associated with the formation of arterial thrombi?

A) von Willebrand's disease
B) Hemophilia
C) Dysfibrinogenemia
D) Diabetes

Question 10

How do red thrombi differ from white thrombi?

A) Their location
B) Their composition
C) Their location and composition
D) Their degree of severity

Question 11

A patient has been taking Coumadin for a recent thrombophilic episode. He follows up with his physician two weeks after starting this treatment. The physician sees evidence of skin necrosis on the patient. What should the physician do next to investigate this finding?

A) Request and have a PT and an APTT drawn
B) Request and have a Protein C antigen assay drawn
C) Request and have a HC-II antigen assay drawn
D) Request and have a Protein S antigen assay drawn

Question 12

Which of the following alterations would most likely be associated with a hypercoagulable state?

A) Excess plasma coagulation proteins
B) Decreased fibrinolytic inhibitors
C) Excess coagulation inhibitors
D) Decreased platelets

Question 13

A patient with thrombophilia has a decreased functional and antigenic activity of protein C. What is the diagnosis?

A) APCR
B) Protein S deficiency
C) Type I PC deficiency
D) Type II PC deficiency

Question 14

Patients with a DVT are at risk for developing which of the following?

A) Transient ischemic attacks
B) Peripheral artery disease
C) Myocardial infarction
D) Pulmonary emboli

Question 15

Mutations in which of the following gene(s) lead to hyperhomocysteinemia?

A) HFE and MTHFR genes
B) CBS and MTHFR genes
C) Prothrombin gene
D) Factor V gene

Question 16

Heparin inhibits coagulation by:

A) Chelating calcium release from platelet granules
B) Catalyzing antithrombin activity
C) Neutralizing labile factors V and VIII
D) Neutralizing the tenase complex

Question 17

What is the usual adjustment for heparin dosage?

A) 2 times the patient's pretreatment baseline PT value
B) 1.5-2.5 times the patient's pretreatment baseline PTT value
C) APTT results between 40-50 seconds
D) 1.0-1.5 times the patient's pretreatment baseling PTT value

Question 18

A 30-year-old patient is diagnosed with a third episode of DVT. He is currently hospitalized and receiving heparin therapy. The physician orders a thrombotic risk battery of tests. What is the most appropriate action that the laboratory professional should take?

A) Call the physician and explain that testing will not be accurate during anticoagulant therapy and during the thrombotic episode
B) Perform the battery of tests in the thrombosis risk profile but note that results are not reliable
C) Perform a PT and an APTT, and, if prolonged, refuse to do the testing
D) Call the physician and explain that this patient is not a candidate for thrombosis risk testing

Question 19

Patients with protein C and/or S deficiencies are at risk for which type of complication?

A) Hemorrhage
B) Delayed bleeding after injury
C) Thrombosis
D) Fibrinolysis

Question 20

A postoperative heart transplant patient has been given unfractionated heparin. Five days postoperative, he develops petechiae and needs multiple dressing changes over his wound site. What tests should be used to assess the patient's clinical status?

A) Platelet count and HIT antibody assay
B) APTT and PT
C) PT and FDP
D) D-dimer and fibrogen

Question 21

Which of the following inherited condition is considered a low risk for a venous thromboembolic event?

A) Homozygous factor V_Leiden
B) Homozygous prothrombin 20210
C) Homozygous AT, PC, or PS deficiency
D) Sickle-cell anemia

Question 22

How does a thrombus become a thromboembolus?

Question 23

Antibodies to which component(s) are thought to complex with the phospholipids resulting in antiphospholipid antibody syndrome are:

A) Homocysteine
B) Fibrinogen and fibrin
C) β₂-glycoprotein-1, prothrombin, PC, PS, and FVII
D) Plasminogen and plasmin

Question 24

Why are clotting and molecular assays both needed for a diagnosis of APCR?

Question 25

A patient is admitted to the local hospital with a pulmonary embolus. He was unconscious when admitted to the emergency department. Ultrasound revealed a large clot in the patient's saphenous vein. Thrombolytic therapy is administered, and eventually the patient's condition stabilizes. Laboratory tests are performed at hospital admission; their results follow: PT: 15.5 sec
INR: 2.85
APTT: 76 sec
Protein C antigen: 14%
Protein C functional activity: 18%
Molecular studies: FV-R506Q present
Based on this information, what is the most probable diagnosis for this patient?

A) PC deficiency and factor V deficiency
B) PS deficiency and factor V deficiency
C) APCR and PC deficiency
D) HC-II deficiency

Question 26

What are microparticles and how do they affect thrombus formation?

Question 27

The reason that thrombolytic agents are not recommended for prolonged anticoagulation therapy is that they:

A) Are weak anticoagulants that often cause repeat thrombotic episodes
B) Are powerful agents that increase the risk of hemorrhage
C) Often need another agent for full anticoagulant effect
D) Are used for prolonged anticoagulation therapy

Question 28

Name the genetic mutation that induces increased concentration of prothrombin in the circulation that leads to increased risk of venous thrombosis.

A) G → A substitution on nucleotide 20210 of the prothrombin gene
B) Lysine to glutamic acid substitution on the sixth position on the beta globin chain
C) Arginine to glutamine substitution at the 506 position of prothrombin
D) Translocation of chromosome 22 onto the long arm of chromosome 9

Question 29

How does the INR standardize the prothrombin time?

Question 30

Why does a patient who had a thrombotic incident receive both heparin and Coumadin for 4-5 days before heparin is discontinued?

A) Heparin is not effective as an anticoagulant without Coumadin.
B) Coumadin requires heparin for its full anticoagulant effect.
C) Coumadin and heparin have a synergistic effect
D) Coumadin 's full effect is not achieved for 4-5 days after initiation because of the half-life of the vitamin K coagulation factors.

Question 31

Which of the following conditions is not associated with an increased tendency for thrombosis?

A) Antiphospholipid antibody syndrome
B) Pregnancy
C) Malignancy
D) Factor VIII deficiency

Question 32

Explain why many patients with an inherited thrombophilia are misdiagnosed.

Question 33

Describe the recommended approach for identifying a lupus anticoagulant:

Question 34

Which of the following best describes the most common cause of hyperhomocysteinemia?

A) Mutations in the CBS gene or MTHFR gene
B) APCR
C) TFPI variant
D) Substitution in the 3' untranslated region of the prothrombin gene (nucleotide 20210)

Question 35

Which of the following mechanisms can lead to an increased risk of thrombosis?

A) Increased concentration of plasminogen activator
B) Deficiency of plasminogen
C) Deficiency of plasminogen activator inhibitor
D) Increased concentration of plasminogen

Question 36

What are the physiological processes involved in hypercoagulability?

Question 37

A patient being treated with heparin therapy has a 65% decrease in platelet count from the baseline count after 6 days of being on the anticoagulant. What is the probable cause of the decrease?

A) DIC
B) TTP
C) HIT
D) APLS

Question 38

Which laboratory test is considered to have a reliable negative predictive value in the diagnosis of DVT?

A) Factor V_Leiden
B) PT
C) tPA
D) D-dimer