Deck 39: Thrombotic Disorders and Laboratory Assessment

Question 1

Which of the following is used to treat DIC?

A)antithrombin and protein C concentrates
B)platelet transfusions and fresh frozen plasma (FFP)
C)heparin
D)all of the above

Answer 1

all of the above

Question 2

Select the next best test to run given the following PTT results on a patient's plasma:

A)dilute Russell's viper venom time
B)factor assays
C)factor V Leiden
D)Bethesda titer

Answer 2

factor assays

Question 3

Which of the following is an expected finding in DIC?

A)thrombocytosis
B)schistocytes on the blood film
C)normal hemoglobin and hematocrit
D)macrocytic red cells

Answer 3

schistocytes on the blood film

Question 4

What tests should be performed on a regular basis on patients receiving therapeutic heparin?

A)PT and hematocrit
B)PTT and white count
C)PTT and platelet count
D)factor assays and platelet count

Question 5

Why does the factor V Leiden mutation increase thrombotic risk?

A)makes factor Va resistant to degradation by activated protein C
B)makes blood more viscous
C)makes factor V more susceptible to activation by thrombin
D)decreases the binding of factor Va to the inhibitor antithrombin

Question 6

A thrombosis risk testing profile is ordered on a patient being treated with warfarin for a blood clot in the leg.Select the best course of action.

A)Run the tests immediately.
B)Reject the order.
C)Perform only the tests for protein C and protein S.
D)Recommend the testing be postponed until the warfarin is discontinued.

Question 7

Why does prothrombin G20210A increase the risk of thrombosis?

A)makes prothrombin activation easier
B)elevates prothrombin levels
C)decreases binding of thrombin by antithrombin
D)decreases binding of plasminogen to prothrombin

Question 8

What is the best method to prevent warfarin-induced skin necrosis during treatment for thrombosis?

A)Use higher dose of warfarin early in treatment.
B)Give the patient injections of protein C.
C)Stop warfarin at the first sign of necrosis.
D)Use heparin for first 5 days in conjunction with warfarin.

Question 9

Which of the following makes a patient more prone to hemorrhage?

A)protein C deficiency
B)acute disseminated intravascular coagulation (DIC)
C)factor V Leiden
D)free protein S deficiency

Question 10

Which of the following results puts the patient at an increased risk for thrombosis?

A)total cholesterol of 180 mg/dL
B)PTT of 25 seconds
C)deficiency of factor V
D)chronically elevated fibrinogen

Question 11

What is the best test to perform if a patient's PTT does not rise after the typical heparin dose?

A)immunoassay for anticardiolipin antibody
B)lipoprotein(a) assay
C)chromogenic antithrombin
D)mixing studies

Question 12

What is important about the test systems used for detection of the lupus anticoagulant?

A)The phospholipid concentration should be high.
B)Ellagic acid should be the PTT activator substance.
C)The patient plasma and normal plasma used for mixing studies should be platelet poor.
D)A 1:1 mix should be performed when the initial test is normal to improve the sensitivity.

Question 13

Which of the following is the cause for most strokes and heart attacks in the United States?

A)hemorrhage
B)thrombocytopenia
C)cancer
D)consequences of thrombotic events

Question 14

A patient has a quantitative D dimer of 800 ng/mL.Which can be ruled out from the following list?

A)DIC
B)deep vein thrombosis
C)pulmonary embolus
D)patient is normal

Question 15

Inappropriate formation of platelets or fibrin clots that obstructs blood vessels is called

A)thrombophilia.
B)thrombosis.
C)embolus.
D)factor V Leiden.

Question 16

Which unusual laboratory finding may be present in sepsis-induced DIC?

A)Fibrinogen may be high because it is an acute phase reactant.
B)Schistocytes are absent because the fever destroys them.
C)D dimer is low because the toxins prevent fibrin lysis.
D)The PT and PTT are low because bacteria interfere with these tests.

Question 17

A 37-year-old female patient has a PTT of 76 seconds (reference range,25 to 37 seconds).Her plasma is mixed 1:1 with normal plasma.An immediate PTT performed on the mix is 74 seconds.Which of the following is the most likely diagnosis?

A)hemophilia A
B)factor VIII inhibitor
C)intrinsic factor deficiency
D)lupus anticoagulant

Question 18

All of the following are associated with an increased risk of thrombosis except

A)high high-density lipoprotein (HDL) cholesterol
B)increased homocysteine
C)immobilization of extremities
D)increased high-sensitivity C-reactive protein

Question 19

Which of the following is an expected finding in DIC?

A)elevated D-dimer and fibrin split products
B)high platelet count
C)low prothrombin time (PT) and PTT
D)low TT

Question 20

A patient who is not on heparin and has no history of a factor deficiency has a prolonged partial thromboplastin time (PTT).Select the test that should be performed next.

A)high-sensitivity C-reactive protein
B)mixing studies for lupus anticoagulant
C)thrombin time (TT)
D)lipid panel

Question 21

A patient arrives at the emergency department complaining of pain in the calf of his left leg and shortness of breath.A "stat" D dimer is ordered.Why is this useful information for this patient's care?

A)An elevated D dimer supports the possibility of deep vein thrombosis.
B)An elevated D dimer is diagnostic for deep vein thrombosis.
C)A normal D dimer is diagnostic for deep vein thrombosis.
D)This was not an appropriate test to order on this patient.

Question 22

What substance is used to activate protein C in the chromogenic assay to determine its concentration?

A)partial thromboplastin
B)a specific snake venom
C)kaolin
D)heparin

Question 23

When the chromogenic assay for antithrombin is performed,which of the following is true?

A)The colored end-product intensity is inversely proportional to the antithrombin concentration.
B)The chromogenic substrate is bound by antithrombin.
C)Warfarin is added to the patient sample before testing to improve sensitivity.
D)Activated protein C competes for the chromogenic substrate, so it must first be selectively removed.