Deck 33: Coagulation Procedures

Question 1

What is the anticoagulant of choice in most coagulation procedures?

A) Sodium heparin
B) Sodium citrate, 3.2%
C) Sodium ethylenediaminetetraacetic acid (EDTA)
D) Sodium fluoride
E) None of the above

Answer 1

Sodium citrate, 3.2%

Question 2

Enzyme-specific synthetic substrates used in coagulation studies are based on the principle of amino acids of the substrate on the protein molecule fitting into the active sites and the binding sites of the __________.

A) Substrate
B) Enzyme
C) Ligan D
D) Hapten
E) None of the above

Answer 2

Enzyme

Question 3

The __________ is a measure of the extrinsic and common pathways of coagulation involving factors II, V, VII, and X (as well as fibrinogen).

A) APTT
B) Prothrombin time (PT)
C) Thrombin time (TT)
D) Reptilase time
E) None of the above

Answer 3

Prothrombin time (PT)

Question 4

Abnormal ristocetin-induced platelet aggregation may occur in patients with:

A) Bernard-Soulier syndrome
B) Platelet storage pool defects
C) Idiopathic thrombocytopenic purpura (ITP)
D) All of the above
E) None of the above

Question 5

The patient should be instructed not to take any aspirin-containing drugs__________ before the bleeding time test.

A) 48 hours
B) 24 hours
C) 1 week
D) 12 hours
E) None of the above

Question 6

The activated partial thromboplastin time (APTT) is a screening test to measure the __________ pathway of coagulation.

A) Intrinsic
B) Extrinsic
C) Common
D) A and C
E) All of the above

Question 7

What is the range of pH for samples used for platelet aggregation studies?

A) 7.0-8.0
B) 6.5-8.5
C) 4.0-6.0
D) 7.0-9.0
E) None of the above

Question 8

Aspirin-containing compounds inhibit the __________ wave of aggregation by inhibiting the release reaction of the platelets.

A) Primary
B) Secondary
C) Tertiary
D) All of the above
E) None of the above

Question 9

The chromogenic anti-factor Xa assay is used to monitor:

A) Coumarin
B) Low molecular weight heparin
C) Unfractionated heparin
D) Vitamin K
E) B and C

Question 10

In performing platelet aggregation studies, hemolyzed specimens cannot be used because red blood cells (RBCs) contain __________.

A) Spectrin
B) Iron
C) ADP
D) Glycoprotein
E) None of the above

Question 11

In platelet aggregation, the addition of an aggregating agent causes the formation of large aggregates of platelets, which corresponds to a(n) __________ in light transmittance when using a platelet aggregometer.

A) Increase
B) Decrease
C) No effect
D) All of the above
E) None of the above

Question 12

Clot-based procedures in coagulation are mostly performed at what temperature?

A) 22°C ± 5°
B) 4°C ± 1°
C) 37°C ± 1°
D) 56°C ± 1°
E) None of the above

Question 13

Platelet aggregation studies use __________.

A) Platelet-rich plasma (250,000-350,000 plt count)
B) Platelet-poor plasma (<10,000 plt count)
C) Cryoprecipitate
D) Whole blood
E) None of the above

Question 14

In patients with severe von Willebrand's disease (vWD), aggregation to __________ is characteristically severely reduced or absent.

A) Serotonin
B) Epinephrine
C) Ristocetin
D) Thrombin
E) None of the above

Question 15

What is the anticoagulant used in a sample to be tested for APTT?

A) Sodium oxalate
B) Sodium citrate, 3.2%
C) Sodium heparin
D) EDTA
E) None of the above

Question 16

The APTT is commonly used to monitor __________ therapy.

A) Coumarin
B) Unfractionated heparin
C) Low molecular weight heparin
D) Vitamin K
E) None of the above

Question 17

__________ is defined as the time taken for a standardized skin wound to stop bleeding.

A) Clot retraction
B) Bleeding time
C) Reptilase time
D) All of the above
E) None of the above

Question 18

The ability of platelets to adhere to one another is a process known as __________.

A) Adhesion
B) Aggregation
C) Retraction
D) All of the above
E) None of the above

Question 19

For coagulation procedures, the ratio of blood to anticoagulant is __________.

A) 5:1
B) 10:1
C) 9:1
D) 1:9
E) None of the above

Question 20

Synthetic chromogenic and fluorogenic assays are available for coagulation studies in the evaluation of:

A) Plasmin
B) Plasminogen activator
C) Antithrombin III
D) Heparin
E) All of the above

Question 21

A thrombin time test was performed and the resulting clotting time exceeded the reference range. A 1:1 mixing study with normal pooled plasma was done that corrected the result to the normal range. Which abnormality is suspected?

A) Thrombocytosis
B) Fibrinogen deficiency
C) Plasmin deficiency
D) Circulating inhibitor
E) None of the above

Question 22

Which is the anticoagulant of choice for samples to be tested in the PT test?

A) Sodium heparin
B) Sodium citrate, 3.2%
C) EDTA
D) Acid citrate dextrose (ACD)
E) None of the above

Question 23

If fibrin is discovered in a citrated plasma sample, the following test(s) will not be affected and can still be run:

A) PT
B) APTT
C) Thrombin time
D) All of the above
E) None of the above

Question 24

In the fibrinogen activity assay, a prolonged clotting time obtained when testing patient plasma indicates:

A) Increased fibrinogen (800 mg/dL or more)
B) Decreased fibrinogen (50 mg/dL or less)
C) Pregnancy
D) A and C
E) None of the above

Question 25

The reptilase test will be abnormally prolonged:

A) In hypofibrinogenemia
B) If heparin is present in the sample
C) When the patient is on anti-vitamin K therapy
D) If the patient has had a recent thrombotic episode
E) All of the above

Question 26

The __________ is the assay used for the one-stage quantitative method for factors VIII, IX, XI, and XII?

A) PT
B) APTT
C) TT
D) Fibrinogen assay
E) None of the above

Question 27

Which anticoagulant is used for samples to be tested in the reptilase test?

A) EDTA
B) Sodium citrate, 3.2%
C) Sodium oxalate
D) Sodium heparin
E) None of the above

Question 28

What is the dilution buffer used in the determination of fibrinogen activity?

A) Electrolyte buffer
B) Tris buffer
C) Owren's Veronal buffer
D) All of the above
E) None of the above

Question 29

Fibrinogen can be quantitatively measured by a modification of the __________ because the latter clotting time of dilute plasma is inversely proportional to the concentration of fibrinogen.

A) PT
B) APTT
C) TT
D) Reptilase time
E) None of the above

Question 30

In the one-stage quantitative assay for factors II, V, VII, and X the __________ is the test system used, with specific-factor-deficient plasmas added to normalize all other factors but the one being measured.

A) PT
B) APTT
C) Whole blood clotting time
D) Fibrinogen test
E) None of the above

Question 31

To diagnose a cause, which steps should be taken if, when performing a thrombin time, the patient's average clotting time significantly exceeds the reference range?

A) Result the first clotting time
B) Run the test using a 1:1 mixture of patient's plasma and normal plasma
C) Run the test using a 1:5 mixture of patient's plasma and normal plasma
D) All of the above
E) None of the above

Question 32

The Clauss fibrinogen assay involves clotting dilutions of both patient's test plasma and calibration plasma with an excess of __________.

A) Thrombin
B) Plasmin
C) Fibrin
D) t-PA
E) None of the above

Question 33

The __________ is the time required for thrombin to convert fibrinogen to an insoluble fibrin clot.

A) PT
B) APTT
C) TT
D) Reptilase time
E) None of the above

Question 34

The PT test is sensitive to the vitamin __________ factors and therefore useful as a means of monitoring oral anticoagulant therapy.

A) K-independent
B) D-dependent
C) K-dependent
D) D-independent
E) None of the above

Question 35

In most one-stage quantitative assay method for factors VIII, IX, XI, and XII, a 1:10 dilution is considered __________ percent factor activity.

A) 50
B) 100
C) 75
D) 25
E) None of the above

Question 36

In patients with __________, the PT is prolonged as a result of a change in the ratio of anticoagulant to plasma.

A) Iron-deficiency anemia
B) Thalassemia
C) Polycythemia
D) Liver disease
E) None of the above

Question 37

Reptilase hydrolyzes the fibrinopeptide __________ from the intact fibrinogen molecule in contrast to thrombin, which hydrolyzes fibrinopeptide __________ from fibrinogen.

A) A, A/B
B) A/A, B
C) A, B
D) B, A
E) None of the above

Question 38

Stabilization of the fibrin clot depends on plasma factor __________, which converts hydrogen bonds to covalent bonds by transamination.

A) X
B) XI
C) XII
D) XIII
E) None of the above

Question 39

The normal adult value for fibrinogen is approximately __________.

A) 50-800 mg/dL
B) 200-400 mg/dL
C) 150-300 mg/dL
D) 100-500 mg/dL
E) None of the above

Question 40

In performing a one-stage quantitative assay method for factor II, results are obtained from an activity curve made from dilutions of normal reference plasma and factor __________ plasma.

A) II
B) II-deficient
C) V
D) V-deficient
E) None of the above

Question 41

Patients with __________ show a decrease in factor VIII antigen.

A) Hemophilia A
B) vWD
C) Female carriers of hemophilia A
D) All of the above
E) None of the above

Question 42

In the von Willebrand's factor (vWF) ristocetin cofactor assay, washed or lyophilized and reconstituted platelets are mixed with dilutions of plasma. Ristocetin is added and the rate of __________ is proportional to von Willebrand activity.

A) Adhesion
B) Aggregation
C) Clot lysis
D) All of the above
E) None of the above

Question 43

In the factor XIII screening test, the presence of a formal clot after 24 hours indicates a plasma factor XIII concentration of __________ of normal.

A) <1%
B) >1%
C) 5-10%
D) 10-20%
E) None of the above

Question 44

Normal D-dimer levels are:

A) 0.5-1.0 µg/mL FEU
B) <0.5 µg/mL FEU
C) 1.0-1.5 µg/mL FEU
D) 1.5-2.0 µg/mL FEU
E) None of the above

Question 45

If a patient's APTT is prolonged, and their PT is normal, this could be due to all of these conditions except:

A) Vitamin K deficiency
B) Hemophilia A
C) Lupus anticoagulant
D) Factor XI deficiency
E) Heparin

Question 46

Measurement of FDPs provides an indirect assay of __________.

A) Coagulation
B) Fibrinolysis
C) Platelet adhesion
D) Platelet aggregation
E) None of the above

Question 47

When a factor deficiency is present, there will be a correction of the abnormal APTT by __________ of normal plasma.

A) 75-90%
B) 50-75%
C) 10-25%
D) 25-50%
E) None of the above

Question 48

If a patient's APTT is normal, but their PT is prolonged, this could be due to:

A) Liver disease
B) Factor VII deficiency
C) Vitamin K deficiency
D) Anti-vitamin K therapy
E) All of the above

Question 49

In the platelet neutralization procedure for lupus anticoagulants (LAs), after mixing LA plasma with freeze-thawed platelet lysate, the __________ will be shortened.

A) PT
B) APTT
C) TT
D) Reptilase time
E) None of the above

Question 50

A weak circulating anticoagulant that prolongs the APTT after incubation at 37°C for 1 hour is typical of:

A) Factor VII inhibitor
B) Factor VIII inhibitor
C) Factor X inhibitor
D) All of the above
E) None of the above

Question 51

In the absence of factor XIII, the hydrogen-bonded fibrin polymers are soluble in __________ or 1% monochloroacetic acid.

A) KOH
B) 5 M urea
C) Hydroxychlorate
D) 5 M boric acid
E) None of the above

Question 52

In the presence of a factor VIII inhibitor, the Bethesda titer should be determined in the management of a patient with __________ when therapy involves Factor VIII concentrates.

A) Hemophilia
B) vWD
C) Thalassemia
D) Iron-deficiency anemia
E) None of the above

Question 53

All of the following interfere with the functional protein S assay performed with mechanical clot detection except:

A) 2 IU/mL unfractionated heparin
B) Activated protein C resistance
C) Lipemia
D) Oral anticoagulants
E) None of the above

Question 54

Which assay of antithrombin (AT-III) involves measurement of the diameter of the precipitate circles from plasma diffused into antibody-containing agarose gel to determine the percent of antithrombin?

A) Chromogenic substrate assay
B) Laurell-rocket electroimmunoassay
C) Radial immunodiffusion
D) Clotting time based on thrombin neutralization
E) None of the above

Question 55

When performing an APTT, the addition of normal plasma __________ the clotting time in the presence of a lupus anticoagulant.

A) Will correct.
B) Will not correct.
C) Will not change.
D) All of the above
E) None of the above

Question 56

Patients with vWD have a vWF activity of __________.

A) 25-100%
B) <30%
C) 50-100%
D) 5-90%
E) None of the above

Question 57

In the enzyme-linked immunosorbent assay (ELISA) measurement of factor VIII-related antigen, the intensity of the color produced is __________ proportional to the amount of antigen present.

A) Indirectly
B) Directly
C) Inversely
D) All of the above
E) None of the above

Question 58

Patients with a homozygous deficiency of factor XIII show dissolution of a fibrin clot within __________ hour(s).

A) 1
B) 2
C) 5
D) 3
E) 4

Question 59

The __________ is useful as a screening test for lupus anticoagulants.

A) APTT
B) PT
C) TT
D) Fibrinogen degradation product (FDP)
E) None of the above

Question 60

vWF activity may become normal in patients with vWD:

A) During inflammation
B) During pregnancy
C) After transfusions with factor VIII
D) All of the above
E) None of the above

Question 61

If a patient's PT is normal and their APTT is prolonged, and corrects with a 1:1 mix with normal plasma, this could be due to:

A) Factor V deficiency
B) Factor II deficiency
C) Factor IX deficiency
D) Factor VII deficiency
E) All of the above