Coagulation Study Questions

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Quizzes Created: 7 | Total Attempts: 107,970

Questions: 58 | Attempts: 5,995 | Updated: Mar 22, 2023

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MLT study questions

Questions and Answers

1.

All of the following conditions cause an increased (prolonged) thrombin time except
- A.
  
  Hypofibrinogenemia
- B.
  
  Increased fibrin-degradation products
- C.
  
  Heparin therapy
- D.
  
  Decreased prothrombin
Correct Answer
D. Decreased prothrombin

Explanation
The question asks for a condition that does not cause an increased thrombin time. Thrombin time measures the time it takes for fibrinogen to be converted into fibrin by the enzyme thrombin. Decreased prothrombin, or low levels of prothrombin, would result in a longer thrombin time because there is less prothrombin available to be converted into fibrin. Therefore, decreased prothrombin is the correct answer as it causes an increased thrombin time.

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2.

The end product of the interaction between platelets and plasma factors, other than fibrinogen, is
- A.
  
  Prothrombin
- B.
  
  Thrombin
- C.
  
  Fibrin
- D.
  
  Factor II
Correct Answer
C. Fibrin

Explanation
When platelets interact with plasma factors, they form a clotting cascade. This cascade involves the conversion of prothrombin to thrombin, which then converts fibrinogen to fibrin. Fibrin is the final product of this interaction and is responsible for the formation of a stable blood clot. Therefore, the correct answer is fibrin.

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3.

Heparin inhibits the clotting of blood by neutralizing the effect of
- A.
  
  Thrombin
- B.
  
  Calcium ions
- C.
  
  Platelets
- D.
  
  Factor VIII
- E.
  
  Factor X
Correct Answer
A. Thrombin

Explanation
Heparin inhibits the clotting of blood by neutralizing the effect of thrombin. Thrombin is an enzyme that plays a crucial role in the clotting process by converting fibrinogen into fibrin, which forms the meshwork of a blood clot. Heparin binds to thrombin and prevents it from carrying out its normal function, thereby preventing the formation of blood clots.

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4.

Defibrinated plasma, in order to clot when mixed with tissue thromboplastin and calcium, requires an outside source of?
- A.
  
  Heparin
- B.
  
  Calcium chloride
- C.
  
  Barium sulfate
- D.
  
  Fibrinogen
Correct Answer
B. Calcium chloride

Explanation
Defibrinated plasma is plasma from which the fibrinogen has been removed, resulting in a liquid that does not clot. In order to clot when mixed with tissue thromboplastin and calcium, an outside source of calcium is required. Calcium chloride is commonly used as the outside source of calcium in clotting assays and experiments. It helps in the activation of the coagulation cascade, leading to the formation of fibrin and clot formation.

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5.

Serum differs from plasma by the loss of
- A.
  
  Factor II
- B.
  
  Factor VII
- C.
  
  Thromboplastin
- D.
  
  Fibrinogen
Correct Answer
D. Fibrinogen

Explanation
Serum differs from plasma by the loss of fibrinogen. Fibrinogen is a protein that is essential for blood clotting. When blood is allowed to clot, fibrinogen is converted into fibrin, which forms a mesh-like structure to trap platelets and form a clot. Plasma contains fibrinogen, while serum is the liquid portion of blood that remains after the clotting process, and thus does not contain fibrinogen. Therefore, fibrinogen is the correct answer as it accurately describes the difference between serum and plasma.

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6.

The substance necessary to convert fibrinogen to fibrin is
- A.
  
  Platelets
- B.
  
  Thromboplastin
- C.
  
  Thrombin
- D.
  
  Prothrombin
Correct Answer
C. Thrombin

Explanation
Thrombin is the enzyme responsible for converting fibrinogen, a soluble plasma protein, into fibrin, an insoluble protein that forms the basis of blood clots. Thrombin is produced from prothrombin, another plasma protein, through a series of enzymatic reactions. Platelets, on the other hand, help in the formation of blood clots by aggregating and adhering to the site of injury, but they do not directly convert fibrinogen to fibrin. Thromboplastin is a complex of proteins and phospholipids that initiates the clotting cascade, leading to the formation of thrombin. Therefore, the correct answer is thrombin.

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7.

Fibrinogen acted on by thrombin forms:
- A.
  
  Fibrin monomers and peptides
- B.
  
  Fibrin monomer and X, Y & D
- C.
  
  Fibrin polymer and XIII
- D.
  
  Fibrin (stable)
Correct Answer
A. Fibrin monomers and peptides

Explanation
When fibrinogen is acted upon by thrombin, it undergoes a process called fibrinolysis, which results in the formation of fibrin monomers and peptides. Thrombin cleaves fibrinogen, releasing fibrinopeptides A and B, which allows the fibrinogen molecules to come together and form fibrin monomers. These monomers then polymerize to form a stable fibrin clot. Therefore, the correct answer is fibrin monomers and peptides.

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8.

The clotting factor dependent on Vitamin K is
- A.
  
  Fibrinogen
- B.
  
  Prothrombin
- C.
  
  Thrombin
- D.
  
  AHG
Correct Answer
B. Prothrombin

Explanation
Prothrombin is the correct answer because it is a clotting factor that is dependent on Vitamin K. Prothrombin is a protein that is produced in the liver and is involved in the blood clotting process. Vitamin K is necessary for the production of certain clotting factors, including prothrombin. Without sufficient Vitamin K, the production of prothrombin is impaired, leading to an increased risk of bleeding.

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9.

The substance active in splitting fibrin, fibrinogen and fragments is
- A.
  
  Plasminogen
- B.
  
  Plasmin
- C.
  
  Peptides
- D.
  
  Thrombin
Correct Answer
B. Plasmin

Explanation
Plasmin is the correct answer because it is an enzyme that is responsible for breaking down fibrin, fibrinogen, and their fragments. Plasminogen is the inactive precursor of plasmin, which is converted to its active form during the clotting process. Once activated, plasmin acts as a proteolytic enzyme, breaking down the fibrin meshwork and dissolving blood clots. Therefore, plasmin is the substance actively involved in splitting fibrin, fibrinogen, and their fragments.

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10.

The intrinsic pathway of the coagulation system begins with the activation of
- A.
  
  Factor II
- B.
  
  Factor I
- C.
  
  Factor XII
- D.
  
  Factor V
- E.
  
  Factor VIII
Correct Answer
C. Factor XII

Explanation
The correct answer is factor XII. The intrinsic pathway of the coagulation system is initiated by factor XII, also known as Hageman factor. Factor XII activates factor XI, which then activates factor IX. This leads to the formation of a complex called the tenase complex, which ultimately activates factor X and triggers the common pathway of coagulation. Therefore, factor XII plays a crucial role in initiating the intrinsic pathway of the coagulation system.

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11.

The extrinsic pathway is triggered by
- A.
  
  Membrane lipoproteins (phospholipoproteins)
- B.
  
  Tissue factor
- C.
  
  Ca2+
- D.
  
  Factor VII
- E.
  
  Both a and b
Correct Answer
E. Both a and b

Explanation
The extrinsic pathway is triggered by both membrane lipoproteins (phospholipoproteins) and tissue factor. These factors initiate the clotting process by activating factor VII and ultimately leading to the formation of a blood clot. The presence of both membrane lipoproteins and tissue factor is necessary for the activation of the extrinsic pathway.

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12.

The common pathway begins with
- A.
  
  Factor X activation
- B.
  
  Factor II activation
- C.
  
  Factor I activation
- D.
  
  Factor XIII activation
- E.
  
  Factor V activation
Correct Answer
A. Factor X activation

Explanation
The common pathway of blood coagulation involves a series of reactions that result in the formation of a blood clot. It begins with the activation of factor X, which is a key enzyme in the clotting cascade. Once activated, factor X initiates a series of reactions that ultimately lead to the activation of factor II, also known as thrombin. Thrombin then converts factor I, fibrinogen, into fibrin, which forms the meshwork of the blood clot. Factor XIII is also activated during this process, which helps to stabilize the clot. Factor V is not directly involved in the common pathway, but it serves as a cofactor for factor X activation.

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13.

The final stage of the coagulation pathway involves the conversion of
- A.
  
  Factor I to Ia
- B.
  
  Factor II to IIa
- C.
  
  Factor V to Va
- D.
  
  Factor I to fibrin clot
- E.
  
  Factor IX to IXa
Correct Answer
D. Factor I to fibrin clot

Explanation
The final stage of the coagulation pathway involves the conversion of factor I to fibrin clot. Factor I, also known as fibrinogen, is a soluble protein that is converted into fibrin during the coagulation process. Fibrin is a fibrous protein that forms a mesh-like network, which helps in the formation of blood clots. This conversion is catalyzed by the enzyme thrombin, which is generated through a series of reactions involving other factors such as factor II, V, and IX. Ultimately, the conversion of factor I to fibrin clot is essential for the formation of a stable blood clot to prevent excessive bleeding.

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14.

Prothrombin is
- A.
  
  A protein formed by the liver in the presence of Vitamin K
- B.
  
  An enzyme that converts fibrinogen into fibrin threads
- C.
  
  The end product of the reaction between fibrinogen and thrombin
- D.
  
  A protein released by platelets during coagulation
Correct Answer
A. A protein formed by the liver in the presence of Vitamin K

Explanation
Prothrombin is a protein formed by the liver in the presence of Vitamin K. Vitamin K is necessary for the synthesis of prothrombin in the liver. Prothrombin plays a crucial role in the blood clotting process. When there is an injury, prothrombin is converted into its active form, thrombin, which then converts fibrinogen into fibrin threads. These fibrin threads form a mesh-like structure that helps in the formation of blood clots to prevent excessive bleeding. Therefore, prothrombin is essential for blood clotting and is formed in the liver with the help of Vitamin K.

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15.

Aspirin ingestion has the following hemostatic effect in a normal person
- A.
  
  Prolongs the bleeding time
- B.
  
  Prolongs the clotting time
- C.
  
  Inhibits factor VIII
- D.
  
  Creates a circulating anticoagulant effect
- E.
  
  No effect
Correct Answer
A. Prolongs the bleeding time

Explanation
Aspirin ingestion prolongs the bleeding time in a normal person. This is because aspirin is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits the production of thromboxane A2, a substance that promotes platelet aggregation and vasoconstriction. By inhibiting thromboxane A2, aspirin reduces platelet aggregation and impairs the formation of a stable clot, leading to a longer bleeding time.

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16.

Fibrin monomers polymerize to form
- A.
  
  Fibrinopeptide A
- B.
  
  Fibrinopeptide B
- C.
  
  Fibrin polymer
- D.
  
  Stable fibrin
Correct Answer
C. Fibrin polymer

Explanation
Fibrin monomers undergo a process called polymerization, where they join together to form a larger structure known as a fibrin polymer. This polymerization is essential for the formation of stable fibrin, which is a key component in blood clotting. Fibrinopeptide A and fibrinopeptide B are small peptides that are cleaved from fibrinogen during the clotting process, but they do not form the final stable fibrin structure. Therefore, the correct answer is fibrin polymer.

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17.

Plasminogen is activated by
- A.
  
  Proteolytic enzymes
- B.
  
  Plasmin
- C.
  
  Fragment X
- D.
  
  Fragment Y
Correct Answer
A. Proteolytic enzymes

Explanation
Plasminogen is activated by proteolytic enzymes. Proteolytic enzymes are responsible for breaking down proteins by cleaving the peptide bonds that hold them together. In the case of plasminogen, proteolytic enzymes cleave it to form plasmin, which is the active form of the enzyme. Plasmin plays a crucial role in the breakdown of blood clots by degrading fibrin, a protein involved in clot formation. Therefore, proteolytic enzymes are essential for the activation of plasminogen and subsequent clot dissolution.

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18.

Activated Protein C acts by
- A.
  
  Precipitating calcium
- B.
  
  Binding calcium
- C.
  
  Activating plasmin
- D.
  
  Inactivating VIIIa
Correct Answer
D. Inactivating VIIIa

Explanation
Activated Protein C acts by inactivating VIIIa. This is an important mechanism in the regulation of blood clotting. VIIIa is a cofactor in the clotting cascade that helps to activate factor X, leading to the formation of thrombin and ultimately the formation of a blood clot. By inactivating VIIIa, Activated Protein C helps to prevent excessive clot formation and maintain proper blood flow.

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19.

Prothrombin is converted to thrombin by
- A.
  
  A complex of activated factors IX and VII and calcium ions
- B.
  
  Calcium ions only
- C.
  
  A complex of phospholipids, factor VII, and calcium ions
- D.
  
  A complex of activated factors X and V, platelet factor 3 and calcium
- E.
  
  None of the above
Correct Answer
D. A complex of activated factors X and V, platelet factor 3 and calcium

Explanation
Prothrombin is converted to thrombin by a complex of activated factors X and V, platelet factor 3, and calcium. This complex of factors plays a crucial role in the coagulation cascade, which is the process by which blood clots are formed. Factors X and V are activated in the presence of calcium ions, and together with platelet factor 3, they convert prothrombin into thrombin. Thrombin then acts on fibrinogen to form fibrin, which forms the meshwork of a blood clot. Therefore, the correct answer is a complex of activated factors X and V, platelet factor 3, and calcium.

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20.

Platelet aggregation is accmplished by the release of
- A.
  
  Proteolytic enzymes
- B.
  
  Phospholipids
- C.
  
  Adenosine diphosphate
- D.
  
  Serotonin
Correct Answer
C. Adenosine dipHospHate

Explanation
Platelet aggregation is the process by which platelets clump together to form a blood clot. Adenosine diphosphate (ADP) plays a crucial role in this process. When platelets are activated, they release ADP, which acts as a signaling molecule to attract and activate other platelets. This leads to the recruitment and aggregation of more platelets at the site of injury or damage, ultimately forming a clot to prevent excessive bleeding. Therefore, ADP is necessary for platelet aggregation to occur.

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21.

Heparin is released from
- A.
  
  Damaged rbcs
- B.
  
  Lymph
- C.
  
  Eosinophils
- D.
  
  Mast cells
Correct Answer
D. Mast cells

Explanation
Mast cells release heparin. Heparin is an anticoagulant that prevents blood clotting. When mast cells are activated, they release heparin along with other substances like histamine and cytokines. This release of heparin helps to prevent the formation of blood clots at the site of injury or inflammation.

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22.

Circulating anticoagulants are
- A.
  
  Inhibitors
- B.
  
  Inactivators
- C.
  
  Natural occurring
- D.
  
  All of the above
Correct Answer
D. All of the above

Explanation
The correct answer is "all of the above" because circulating anticoagulants can act as inhibitors, inactivators, and can also occur naturally. Circulating anticoagulants refer to substances in the blood that prevent or slow down the process of blood clotting. These substances can be naturally occurring in the body, or they can be introduced through medication or other external factors. They work by inhibiting or inactivating certain clotting factors or enzymes involved in the clotting process. Therefore, all the given options accurately describe the characteristics of circulating anticoagulants.

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23.

Which of the following is a source of error that can affect most coagulation procedures?
- A.
  
  Improper specimen storage
- B.
  
  Improperly reconstituting and storing test reagents
- C.
  
  Improper temperature of reaction
- D.
  
  Improper timing of a test
- E.
  
  All of the above
Correct Answer
E. All of the above

Explanation
All of the options listed can be sources of error that can affect most coagulation procedures. Improper specimen storage can lead to degradation of the sample, affecting the accuracy of the results. Improperly reconstituting and storing test reagents can result in incorrect concentrations or loss of activity, impacting the reliability of the test. Improper temperature of reaction can alter the kinetics of coagulation, leading to inaccurate results. Improper timing of a test can affect the interpretation of clotting times and other parameters. Therefore, all of these factors can contribute to errors in coagulation procedures.

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24.

In specimen collection, leaving a tourniquet on too long immediately prior to doing a venipuncture can result in:
- A.
  
  Hemoconcentration
- B.
  
  In vivo clotting
- C.
  
  The vein collapsing
- D.
  
  A hematoma
Correct Answer
A. Hemoconcentration

Explanation
Leaving a tourniquet on too long immediately prior to doing a venipuncture can result in hemoconcentration. This occurs because the tourniquet restricts blood flow, causing an accumulation of blood cells and proteins in the area. This can lead to an increased concentration of these components in the blood sample, potentially affecting the accuracy of laboratory test results.

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25.

The proper proportion (in parts) of blood to anticoagulant in the PTT and Protime is
- A.
  
  2:1
- B.
  
  3:1
- C.
  
  5:1
- D.
  
  9:1
Correct Answer
D. 9:1

Explanation
The correct answer is 9:1. In the PTT and Protime tests, a specific proportion of blood to anticoagulant is required to ensure accurate results. A higher ratio of anticoagulant to blood helps prevent blood clotting during the testing process. Therefore, a ratio of 9 parts anticoagulant to 1 part blood is necessary to maintain the proper conditions for these tests.

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26.

Of the following tests, which one should be drawn last:
- A.
  
  EDTA - CBC
- B.
  
  Heparin - pH
- C.
  
  Citrate - PTT
- D.
  
  Clot tube - CK
Correct Answer
A. EDTA - CBC

Explanation
The correct answer is EDTA - CBC. EDTA is an anticoagulant that prevents blood clotting and is commonly used for CBC (Complete Blood Count) tests. CBC tests measure various components of blood, including red blood cells, white blood cells, and platelets. Drawing the EDTA tube last ensures that the blood sample is not contaminated with anticoagulants from other tubes, which could affect the accuracy of the CBC results. Therefore, it is important to draw the EDTA tube after the other tests to obtain reliable CBC measurements.

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27.

If a protime vacutainer was not filled with blood, the results would be
- A.
  
  Unaffected
- B.
  
  Normal
- C.
  
  Shortened
- D.
  
  Prolonge
Correct Answer
D. Prolonge

Explanation
If a protime vacutainer was not filled with blood, the results would be prolonged. This is because the protime test measures the time it takes for blood to clot. If the vacutainer is not filled with blood, there would be no blood sample to test and therefore no clotting time could be measured. This would result in a prolonged or delayed test result.

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28.

The reagent used for PTT:
- A.
  
  Phospholipid
- B.
  
  Tissue thromboplastin
- C.
  
  Heparin
- D.
  
  Thrombin
Correct Answer
A. pHospHolipid

Explanation
Phospholipid is the correct answer for the reagent used for PTT (Partial Thromboplastin Time) test. PTT is a blood test that measures the time it takes for blood to clot. Phospholipids are essential components of cell membranes and play a crucial role in the coagulation process. In the PTT test, phospholipids are added to the blood sample to activate the intrinsic pathway of coagulation. By measuring the time it takes for clot formation, the PTT test helps in evaluating the clotting factors and detecting any abnormalities in the coagulation process.

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29.

The test that detects the presence of non-specific IgG inhibitaors of phospholipid
- A.
  
  Thrombin time
- B.
  
  Protime
- C.
  
  PTT
- D.
  
  Lupus anticoagulants
Correct Answer
D. Lupus anticoagulants

Explanation
Lupus anticoagulants are antibodies that interfere with the normal clotting process in the body. These antibodies target phospholipids, which are essential for blood clotting. The test mentioned in the question is specifically designed to detect the presence of non-specific IgG inhibitors of phospholipid, which are characteristic of lupus anticoagulants. Therefore, the correct answer is lupus anticoagulants.

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30.

The bleeding time test measures:
- A.
  
  The ability of platelets to stick together
- B.
  
  Platelet adhesion and aggregation on locally injured vascular subendothelium
- C.
  
  The quantity and quality of platelets
- D.
  
  Antibodies against platelets
- E.
  
  Both a and b
Correct Answer
B. Platelet adhesion and aggregation on locally injured vascular subendothelium

Explanation
The bleeding time test measures platelet adhesion and aggregation on locally injured vascular subendothelium. This test evaluates how well platelets stick together and form a clot in response to a vascular injury. It helps assess the function of platelets in preventing excessive bleeding. The test does not measure the quantity and quality of platelets or the presence of antibodies against platelets. Therefore, the correct answer is platelet adhesion and aggregation on locally injured vascular subendothelium.

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31.

A lower temperature than optimum, when performing a prothrombin time, will result in
- A.
  
  Shorter time
- B.
  
  Longer time
- C.
  
  No effect
Correct Answer
A. Shorter time

Explanation
A lower temperature than optimum when performing a prothrombin time will result in a shorter time because temperature affects the rate of chemical reactions. Prothrombin time measures the time it takes for blood to clot, and lower temperatures slow down the clotting process. This means that it will take less time for the blood to clot at a lower temperature compared to the optimum temperature, resulting in a shorter prothrombin time.

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32.

If a protime or PTT cannot be run immediately, it is best to
- A.
  
  Wait to centrifuge the whole blood
- B.
  
  Refrigerate the whole blood
- C.
  
  Centrifuge the whole blood, decant and freeze plasma
- D.
  
  Centrifuge the whole blood, then refrigerate
Correct Answer
C. Centrifuge the whole blood, decant and freeze plasma

Explanation
When a protime or PTT test cannot be run immediately, it is best to centrifuge the whole blood, decant and freeze the plasma. This is because the protime and PTT tests require plasma, which is the liquid component of blood. By centrifuging the whole blood, the red blood cells and other cellular components are separated from the plasma. Decanting refers to carefully pouring off the plasma while leaving behind the cellular components. Freezing the plasma preserves it for future testing, ensuring accurate results when the protime or PTT test can be performed. Refrigerating the whole blood or centrifuging the whole blood and then refrigerating it would not preserve the plasma for testing purposes.

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33.

The normal value for the protime is
- A.
  
  8-10 seconds
- B.
  
  11-14 seconds
- C.
  
  20-30 seconds
- D.
  
  Under 45 seconds
Correct Answer
B. 11-14 seconds

Explanation
The normal value for the protime is 11-14 seconds. This range indicates the average time it takes for blood to clot. A protime test measures the activity of certain proteins in the blood that are involved in the clotting process. If the protime is within this range, it suggests that the clotting function is normal. Values outside this range may indicate an increased risk of bleeding or clotting disorders.

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34.

The partial thromboplastin reagent used in the PTT test is a substitute for
- A.
  
  Platelet factor
- B.
  
  Calcium chloride
- C.
  
  Thrombin
- D.
  
  Fibrin
Correct Answer
A. Platelet factor

Explanation
The partial thromboplastin reagent used in the PTT test is a substitute for platelet factor. Platelet factor is a component released by platelets during the clotting process to initiate the formation of a blood clot. In the PTT test, the reagent is used to mimic the role of platelet factor and measure the time it takes for the blood to clot. By using a substitute for platelet factor, the PTT test can assess the functionality of the intrinsic pathway of coagulation, which is important for diagnosing bleeding disorders.

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35.

The PTT is different from the prothrombin time in that it measures the
- A.
  
  Extrinsic clotting system
- B.
  
  Intrinsic clotting system
- C.
  
  Factor VII and platelets
- D.
  
  Fibrinogen
Correct Answer
B. Intrinsic clotting system

Explanation
The PTT (partial thromboplastin time) is a laboratory test that measures the intrinsic clotting system, which includes factors VIII, IX, XI, and XII, as well as prekallikrein and high molecular weight kininogen. This system is responsible for the formation of a blood clot within the body. The prothrombin time, on the other hand, measures the extrinsic clotting system, which involves factors VII, X, V, II, and fibrinogen. Therefore, the correct answer is that the PTT measures the intrinsic clotting system.

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36.

Automated mechanical end-point detection systems rely on the principle of
- A.
  
  Clot elasticity
- B.
  
  Fibrin adhesion
- C.
  
  Conduction or impedance of an electrical current by fibrin
- D.
  
  Changes in optical density
- E.
  
  None of the above
Correct Answer
C. Conduction or impedance of an electrical current by fibrin

Explanation
Automated mechanical end-point detection systems rely on the principle of conduction or impedance of an electrical current by fibrin. This means that these systems use electrical current to measure the conductivity or impedance of fibrin, which allows them to detect when a clot has formed. By monitoring the changes in conductivity or impedance, these systems can accurately determine the end-point of clot formation. This principle is important in various medical and laboratory settings where clot detection is necessary, such as in coagulation tests or blood clotting studies.

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37.

When performing a bleeding time, the usual puncture site is the
- A.
  
  Finger
- B.
  
  Forearm
- C.
  
  Heel
- D.
  
  Ear lobe
- E.
  
  Big toe
Correct Answer
B. Forearm

Explanation
The usual puncture site for performing a bleeding time is the forearm. This is because the forearm contains a good blood supply and has a flat surface, making it easier to apply pressure and obtain a reliable blood sample. Puncturing the finger may cause excessive bleeding and difficulty in applying pressure, while puncturing the heel, ear lobe, or big toe may not provide an adequate blood supply for the test.

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38.

A source of error when using a photo-optical endpoint detection method in coagulation studies can be
- A.
  
  Lipemia
- B.
  
  Hemolysis
- C.
  
  Icterous
- D.
  
  A and b
- E.
  
  All of the above
Correct Answer
E. All of the above

Explanation
The correct answer is "all of the above." When using a photo-optical endpoint detection method in coagulation studies, lipemia, hemolysis, and icterous samples can all be sources of error. Lipemia refers to the presence of excessive fat in the blood, which can interfere with the accuracy of optical measurements. Hemolysis occurs when red blood cells break down, releasing their contents into the plasma, which can also affect the optical readings. Icterus, or jaundice, is the yellowing of the skin and eyes due to elevated levels of bilirubin, which can interfere with the optical detection method. Therefore, all three factors can introduce errors in coagulation studies when using a photo-optical endpoint detection method.

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39.

The PTT test is a good measure of quantity and function of which of the following factors except
- A.
  
  VIII and IX
- B.
  
  VII and XIII
- C.
  
  I and II
- D.
  
  V and X
Correct Answer
B. VII and XIII

Explanation
The PTT test is used to measure the quantity and function of factors VIII and IX, which are important for blood clotting. Therefore, the correct answer is VII and XIII, as these factors are not measured by the PTT test.

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40.

The thrombin test measures
- A.
  
  Thrombin
- B.
  
  Prothrombin
- C.
  
  Fibrinogen
- D.
  
  Factor XIII
Correct Answer
C. Fibrinogen

Explanation
The thrombin test measures fibrinogen levels. Fibrinogen is a protein that is converted into fibrin during the blood clotting process. Thrombin is an enzyme that plays a crucial role in this conversion. By measuring fibrinogen levels, the thrombin test helps to assess the ability of blood to form clots. This test is commonly used to diagnose and monitor conditions related to blood clotting disorders, such as deep vein thrombosis or disseminated intravascular coagulation.

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41.

The adhesiveness of platelets is measured, in vitro, by their ability to adhere to
- A.
  
  Ristocetin
- B.
  
  Damaged cells
- C.
  
  Glass beads
- D.
  
  Polyvinyl tubing
Correct Answer
C. Glass beads

Explanation
Platelets are small cell fragments that play a crucial role in blood clotting. In vitro, their adhesiveness can be measured by observing their ability to adhere to certain surfaces. Glass beads are commonly used for this purpose as they provide a smooth and non-reactive surface for platelets to adhere to. This allows researchers to study platelet adhesion and aggregation, which is important in understanding blood clot formation and related disorders. Using glass beads as a substrate provides a standardized and reliable method for measuring platelet adhesiveness in a controlled laboratory setting.

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42.

Hyperfibrinogenemia may develop in
- A.
  
  Hemophiliacs
- B.
  
  Vitamin K deficiencies
- C.
  
  Late stages of pregnancy
- D.
  
  Sickle cell anemia
Correct Answer
C. Late stages of pregnancy

Explanation
Hyperfibrinogenemia is a condition characterized by high levels of fibrinogen in the blood. Fibrinogen is a protein involved in blood clotting. During the late stages of pregnancy, the body naturally increases its production of fibrinogen as a protective mechanism to prevent excessive bleeding during childbirth. This physiological response can lead to hyperfibrinogenemia in pregnant women. Therefore, late stages of pregnancy can be a potential cause of hyperfibrinogenemia.

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43.

The following laboratory results were obtained for a patient with an inherited autosomal dominant trait: Platelet adhesiveness - abnormal PT - normal PTT - normal Bleeding time - prolonged These findings are most consistent with
- A.
  
  Hemolytic disease of the newborn
- B.
  
  Factor X deficiency
- C.
  
  Factor XI deficiency
- D.
  
  VonWillebrand's disease
Correct Answer
D. VonWillebrand's disease

Explanation
The laboratory results indicate that the patient has abnormal platelet adhesiveness and a prolonged bleeding time. This suggests a defect in the formation of platelet plugs, which is a characteristic of VonWillebrand's disease. Factor X deficiency and factor XI deficiency are not consistent with the normal PT and PTT results. Hemolytic disease of the newborn does not directly affect platelet adhesiveness or bleeding time. Therefore, the most consistent explanation for the given laboratory results is VonWillebrand's disease.

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44.

Thrombocytopenia may be associated with the prolongation of all of the following except:
- A.
  
  Bleeding time
- B.
  
  Ristocetin assay
- C.
  
  Platelet aggregometry
- D.
  
  PTT
Correct Answer
D. PTT

Explanation
Thrombocytopenia is a condition characterized by a low platelet count, which can lead to an increased risk of bleeding. Bleeding time, ristocetin assay, and platelet aggregometry are all tests that assess platelet function and can be prolonged in individuals with thrombocytopenia. However, PTT (Partial Thromboplastin Time) is a test that measures the time it takes for blood to clot and is primarily affected by deficiencies in clotting factors, not platelet count. Therefore, PTT is not typically prolonged in individuals with thrombocytopenia.

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45.

A defect in factor IX causes which of the following diseases
- A.
  
  Hemophilia A
- B.
  
  Hemophilia B
- C.
  
  Afibrinogenemia
- D.
  
  Hypothrombinemia
Correct Answer
B. HemopHilia B

Explanation
Hemophilia B is caused by a defect in factor IX, a clotting protein in the blood. This defect leads to impaired blood clotting and excessive bleeding. Hemophilia A, on the other hand, is caused by a defect in factor VIII. Afibrinogenemia is a condition characterized by the absence of fibrinogen, a protein necessary for blood clotting. Hypothrombinemia refers to a deficiency in thrombin, an enzyme involved in blood clotting. Therefore, the correct answer is hemophilia B, as it is specifically associated with a defect in factor IX.

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1
0
46.

Coumadin drugs produce anticoagulation by interfering with the reaction of
- A.
  
  Thrombin and fibrinogen
- B.
  
  AHG, PTA & XIII
- C.
  
  XI & XII
- D.
  
  II, VII, IX & X
Correct Answer
D. II, VII, IX & X

Explanation
Coumadin drugs produce anticoagulation by interfering with the reaction of II, VII, IX, and X. These are all clotting factors involved in the coagulation cascade, which is the series of reactions that leads to the formation of a blood clot. By inhibiting these clotting factors, Coumadin prevents the formation of blood clots and reduces the risk of thrombosis.

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47.

The hereditary gene for hemophilia is carried on the
- A.
  
  X chromosome of the female
- B.
  
  X chromosome of the male
- C.
  
  Y chromosome of the male
- D.
  
  X & Y chromosomes of the male
Correct Answer
A. X chromosome of the female

Explanation
Hemophilia is a genetic disorder that is caused by a mutation in the gene responsible for producing clotting factors. This gene is located on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. Since the gene for hemophilia is carried on the X chromosome, females have two copies of the gene, making them carriers of the disorder. Males, on the other hand, only have one copy of the X chromosome, so if they inherit the mutated gene, they will develop hemophilia. Therefore, the correct answer is "x chromosome of the female."

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48.

Hemophilia A is a condition which results in a deficiency of factor
- A.
  
  I
- B.
  
  II
- C.
  
  VIII
- D.
  
  IX
Correct Answer
C. VIII

Explanation
Hemophilia A is a condition that causes a deficiency of factor VIII. Factor VIII is a protein that plays a crucial role in blood clotting. Without enough factor VIII, blood clotting is impaired, leading to prolonged bleeding episodes and difficulty in stopping bleeding. Hemophilia A is an inherited disorder that primarily affects males, as the faulty gene responsible for producing factor VIII is located on the X chromosome. Treatment for hemophilia A involves replacing the missing factor VIII through regular infusions or injections.

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49.

A factor deficiency noted by prolongation of the protime and PTT is
- A.
  
  VII & IX
- B.
  
  VIII & XI
- C.
  
  VIII & XII
- D.
  
  V & VII
Correct Answer
D. V & VII

Explanation
A factor deficiency noted by prolongation of the protime and PTT indicates a deficiency in both Factor V and Factor VII. These factors are essential for the normal functioning of the coagulation cascade. When either of these factors is deficient, it leads to impaired blood clotting, resulting in prolonged prothrombin time (protime) and partial thromboplastin time (PTT). The other options, VIII & XI, VIII & XII, and V & VII, do not fully explain the observed prolongation of both protime and PTT.

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2
0
50.

An elevated FDP (fibrin degradation products) suggest:
- A.
  
  Lupus
- B.
  
  Cortisone therapy
- C.
  
  PA
- D.
  
  DIC
Correct Answer
D. DIC

Explanation
An elevated FDP (fibrin degradation products) suggests DIC (disseminated intravascular coagulation). DIC is a serious condition characterized by abnormal blood clotting throughout the body, leading to the formation of small blood clots that can block blood vessels and disrupt normal blood flow. As a result of this excessive clotting, fibrin degradation products are released into the bloodstream. Therefore, an elevated level of FDP indicates the presence of DIC.

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Apr 30, 2013

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Coagulation Study Questions

All of the following conditions cause an increased (prolonged) thrombin time except

The end product of the interaction between platelets and plasma factors, other than fibrinogen, is

Heparin inhibits the clotting of blood by neutralizing the effect of

Defibrinated plasma, in order to clot when mixed with tissue thromboplastin and calcium, requires an outside source of?

Serum differs from plasma by the loss of

The substance necessary to convert fibrinogen to fibrin is

Fibrinogen acted on by thrombin forms:

The clotting factor dependent on Vitamin K is

The substance active in splitting fibrin, fibrinogen and fragments is

The intrinsic pathway of the coagulation system begins with the activation of

The extrinsic pathway is triggered by

The common pathway begins with

The final stage of the coagulation pathway involves the conversion of

Prothrombin is

Aspirin ingestion has the following hemostatic effect in a normal person

Fibrin monomers polymerize to form

Plasminogen is activated by

Activated Protein C acts by

Prothrombin is converted to thrombin by

Platelet aggregation is accmplished by the release of

Heparin is released from

Circulating anticoagulants are

Which of the following is a source of error that can affect most coagulation procedures?

In specimen collection, leaving a tourniquet on too long immediately prior to doing a venipuncture can result in:

The proper proportion (in parts) of blood to anticoagulant in the PTT and Protime is

Of the following tests, which one should be drawn last:

If a protime vacutainer was not filled with blood, the results would be

The reagent used for PTT:

The test that detects the presence of non-specific IgG inhibitaors of phospholipid

The bleeding time test measures:

A lower temperature than optimum, when performing a prothrombin time, will result in

If a protime or PTT cannot be run immediately, it is best to

The normal value for the protime is

The partial thromboplastin reagent used in the PTT test is a substitute for

The PTT is different from the prothrombin time in that it measures the

Automated mechanical end-point detection systems rely on the principle of

When performing a bleeding time, the usual puncture site is the

A source of error when using a photo-optical endpoint detection method in coagulation studies can be

The PTT test is a good measure of quantity and function of which of the following factors except

The thrombin test measures

The adhesiveness of platelets is measured, in vitro, by their ability to adhere to

Hyperfibrinogenemia may develop in

The following laboratory results were obtained for a patient with an inherited autosomal dominant trait: Platelet adhesiveness - abnormal PT - normal PTT - normal Bleeding time - prolonged These findings are most consistent with

Thrombocytopenia may be associated with the prolongation of all of the following except:

A defect in factor IX causes which of the following diseases

Coumadin drugs produce anticoagulation by interfering with the reaction of

The hereditary gene for hemophilia is carried on the

Hemophilia A is a condition which results in a deficiency of factor

A factor deficiency noted by prolongation of the protime and PTT is

An elevated FDP (fibrin degradation products) suggest: