HEMA 2 EXAM

Question 1

Heparin inhibits clotting by:

a. Preventing the activation of prothrombin
b. Chelation of calcium
c. Causing the liver synthesis of non-functional factors
d. Enhancing the function of antithrombin

Answer 1

Enhancing the function of antithrombin

*heparin forms a complex with
antithrombin to inhibit coagulation. The heparin-antithrombin complex rapidly inhibits thrombin and other serine proteases. Several
anticoagulants, such as EDTA and sodium citrate inhibit coagulation by chelation of
calcium.

Question 2

A specimen is received for PT and APTT. The 5mL tube has only 3mL of blood in it. Expected results are:

a. PT and APTT are both falsely shortened
b. PT and APTT are both falsely prolonged
c. PT and APTT are both unaffected
d. PT is unaffected, APTT is falsely shortened

Answer 2

PT and APTT are both falsely prolonged

*A 9:1 ratio of blood to
anticoagulant is needed for sodium citrate to bind all available calcium in the blood sample and prevent coagulation. When the 9:1 ratio is not maintained due to the tube being underfilled, excess sodium citrate present will bind reagent calcium in the test system. This will cause falsely prolonged PT and APTT results.

Question 3

Which of the following initiates the in vivo coagulation by activation of factor VII?

a. Protein C
b. Tissue factor
c. Plasmin activator
d. Thrombomodulin

Answer 3

Tissue factor

*In vivo, activation of coagulation occurs on the surface of activated platelets or cells that have tissue factor. Tissue factor is found on the surface of many cells outside the vascular system (extrinsic). Upon vascular injury, Tissue factor is exposed to the vascular system. Tissue factor has a high affinity for factors VII and VIIa. Tissue factor would now activate factor VII to VIIa to form the TF-VIIa complex.

Question 4

Which ratio of blood-to-anticoagulant is correct for coagulation procedures?

a. 1:9
b. 4:1
c. 1:4
d. 9:1

Answer 4

9:1

*the optimum ratio of anticoagulant to blood is one part anticoagulant to nine parts of blood. The anticoagulant supplied in this amount is sufficient to bind all the available calcium, thereby preventing clotting.

Question 5

The most important step in phlebotomy is:

a. Labeling of specimen
b. Following the order of draw
c. Identifying the patient
d. Selecting the proper needle length

Answer 5

Identifying the patient

*Patient ID, the process of verifying a patient’s identity, is the most important step
in specimen collection. Obtaining a specimen from the wrong patient can have serious, even fatal, consequences, especially specimens for type and crossmatch prior to blood transfusion.

Question 6

Which test would be abnormal for factor X deficiency?

a. PT only
b. APTT only
c. PT and APTT
d. Thrombin time

Answer 6

PT and APTT

*factor X is involved in the common pathway of the coagulation cascade; therefore, its deficiency prolongs both the PT and APTT.

Question 7

Laboratory tests requested on a patient scheduled for early morning surgery include
CBC with platelet count. An automated platelet count performed on the specimen is 57 x 109/L. In the monolayer area of the PBS, there is approximately 12 platelets per oil immersion field, many of which are encircling neutrophils. Controls are in range. Based on this information, the best course of action is

a. Report all the results.
b. Alert the physician immediately so cancellation of surgery can be considered.
c. Thoroughly mix specimen and repeat platelet count.
d. Redraw specimen using 3.2% sodium citrate as anticoagulant.

Answer 7

Redraw specimen using 3.2% sodium citrate as anticoagulant.

*platelets encircling neutrophils is a phenomenon referred to as “platelet satellitosis”. This pseudothrombocytopenia occurs when blood of some individuals is anticoagulated with EDTA. Recollecting the
specimen using 3.2% sodium citrate often corrects this problem. If sodium citrate is
used, platelet count should be multiplied by 1.1 for reporting purposes. Multiplying by 1.1
adds back the 10% loss of platelets seen when sodium citrate is used.

Question 8

Which of the following factor is not vitamin K dependent?

a. Factor V
b. Factor II
c. Factor IX
d. Protein C

Answer 8

Factor V

*The vitamin K dependent factors are factors IX, X, VII, and II which are also known as the prothrombin group. Protein C
and S, which are inhibitors of coagulation, are also vitamin K dependent.

Question 9

Which of the following will not cause thrombin time to be prolonged?

a. Fibrin degradation products
b. Heparin
c. Factor I deficiency
d. Factor II deficiency

Answer 9

Factor II deficiency

*The thrombin time is a test that
measures fibrinogen. Thrombin reagent is added to undiluted plasma, and the time it takes for fibrinogen to convert to fibrin is measured. Factor II cannot be measured in the thrombin time because the reagent used is its active form, thrombin.

Question 10

All of the following causes thrombocytopenia, except:

a. Splenomegaly
b. Chemotherapy
c. Increased thrombopoietin
d. Aplastic anemia

Answer 10

Increased thrombopoietin

*Thrombopoietin is the major
humoral factor involves in platelet production. Increased thrombopoietin results in
thrombocytosis; decreased amounts result to thrombocytopenia.

Question 11

The recommended microscope for performing manual platelet count is:

a. Electron
b. Dark field
c. Light
d. Phase contrast

Answer 11

Phase contrast

phase contrast microscopy is
currently recommended for manual platelet counts. This allows satisfactory discrimination between platelet and debris. Light microscopy can be used however, differentiating platelets from debris can be difficult.

Question 12

The intrinsic pathway of coagulation begins with the activation of ___ in the early stage.

a. Factor II
b. Factor I
c. Factor XII
d. Factor V

Answer 12

Factor XII

The intrinsic pathway of
coagulation begins with the activation of factor XII (a zymogen, inactivated serine protease) which becomes factor XIIa (activated serine protease) after exposure to endothelial collagen.

Question 13

The final common pathway of the intrinsic- extrinsic pathway is:

a. Factor X activation
b. Factor II activation
c. Factor I activation
d. Factor XIII activation

Answer 13

Factor X activation

Both the extrinsic and intrinsic
pathways meet at a shared point to continue coagulation, the common pathway. The final common pathway begins with the activation of factor X to factor Xa.

Question 14

For manual platelet count, the most common dilution is:

a. 1:10
b. 1:20
c. 1:100
d. 1:200

Answer 14

1:100

Procedure for manual platelet
count includes making a 1:100 dilution by placing 20uL of well-mixed blood in 1980uL of 1% ammonium oxalate. Mix the dilution thoroughly and charge the chamber. Place the charged hemacytometer in a moist chamber for 15 minutes to allow platelets to settle.

Question 15

Stress platelets are also known as:

a. Reticulated platelets
b. Small platelets
c. Resting platelets
d. Giant platelets

Answer 15

Reticulated platelets

Reticulated platelets, sometimes
known as stress platelets, appear in compensation for thrombocytopenia. Reticulated platelets are markedly larger than ordinary mature circulating platelets; their diameter in PBS exceeds 6um, and their MPV reaches 12 – 14fL.

Question 16

For manual platelet count, the filled counting chamber should be allowed to settle for ___ prior to counting.

a. 5 mins
b. 10 mins
c. 15 mins
d. 20 mins

Answer 16

15 mins

*Procedure for manual platelet
count includes making a 1:100 dilution by placing 20uL of well-mixed blood in 1980uL of 1% ammonium oxalate. Mix the dilution thoroughly and charge the chamber. Place the charged hemacytometer in a moist chamber for 15 minutes to allow platelets to settle.

Question 17

What is the area counted for manual platelet count?

a. 0.2mm2
b. 1 mm2
c. 1.5 mm2
d. 4 mm2

Answer 17

1 mm2

*In the procedure for manual
platelet count, the number of platelets in the 25 small squares in the center square of the grid is counted. The area of this center square is 1mm2

Question 18

Delta check means:

a. Documenting all the results of the quality control checks
b. Comparing the current test results with the previous one
c. Checking the wristband with the requisition
d. Reporting new infection control precautions.

Answer 18

Comparing the current test results with the previous one

*The difference between a patient’s present laboratory result and consecutive previous results that exceeded predefined limit is referred to as Delta check. Delta checks are investigated before reporting a patient result. Delta checks are investigated by the laboratory internally to rule out errors, for
example, mislabeling of specimen.

Question 19

Fibrinogen is converted to fibrin monomers by:

a. Prothrombin
b. Calcium ions
c. Thrombin
d. Factor XIIIa

Answer 19

Thrombin

Thrombin is the activated form of prothrombin. Thrombin acts on the soluble plasma fibrinogen to form a fibrin clot, which is stabilized by activated factor XIII (XIIIa).

Question 20

Which of the following is the largest cell in the bone marrow?
I. Megakaryoblast
II. Promegakaryocyte
III. Megakaryocyte
IV. Mast cell

a. II
b. III
c. I
d. IV

Answer 20

III

*Megakaryocyte is the largest cell in the bone marrow, measuring 30 to 50 um and having a multilobed nucleus. Its cytoplasm is composed of platelets, which are released to the blood through the extension of the proplatelet processes into the vascular sinuses of the bone marrow. Identified and enumerated microscopically at low (10x) power on a bone marrow aspirate smear.

Question 21

Which factors are in the contact group?
1. Factor XI
2. Factor XII
3. Prekallikrein
4. HMWK

a. 1 and 2
b. 1, 2, and 3
c. 1 and 3
d. 1, 2, 3, 4

Answer 21

1, 2, 3, 4

*the contact group are those
coagulation factors that are stable, and not consumed during coagulation. They are also not absorbed by barium sulfate or aluminum hydroxide. They are so named “contact factors” because they are activated by contact with negatively charged foreign surfaces. This includes factors XII, XI, HMWK, and PK.

Question 22

All of the following are synthesized in the liver,
except:

a. Factor VIII
b. Plasminogen
c. Protein C
d. VWF

Answer 22

VWF

*The liver produces most of the clotting factors as well as inhibitors to clotting. One of the few hemostatic proteins not
produced by the liver is Von Willebrand factor, which is produced by the endothelial cells and megakaryocytes.

Question 23

Which test would be abnormal for patients with Stuart Prower deficiency?

a. PT only
b. PTT only
c. Thrombin time
d. PT and APTT

Answer 23

PT and APTT

*Stuart-Prower factor or factor X is involved in the common pathway of the coagulation cascade; therefore, its deficiency prolongs both the PT and APTT.

Question 24

Clinical conditions associated with DIC:

a. Acute infections
b. Snake bites
c. M3 leukemia
d. All of the above

Answer 24

All of the above

The clinical conditions associated with DIC are (TOMASA) Tissue trauma, Obstetric complications, Mucus-secreting tumors, Acute infections, Snake bites, Acute promyelocytic leukemia.

Question 25

If samples are left at room temperature for an extended time, factors __ and __ are likely to deteriorate I. Factors V II. Factors VI III. Factors VII IV. Factors VIII a. I and II b. II and III c. III and IV d. I and IV

Answer 25

I and IV *Factors V and VIII are both labile factors. Factor V is an extremely labile globulin protein that deteriorates rapidly, having a half-life of only 16 hours. Factor VIII is extremely labile, with a 50% loss within 12 hours at 4 ̊C in vitro and similar 50% loss in vivo within 8 to 12 hours after transfusion.

Question 26

In storage pool disease, platelets are primarily deficient in: a. Platelet factor b. ADP c. Thrombosthenin d. Thromboxane A2

Answer 26

ADP Platelets in storage pool disease are deficient in dense granules. The platelets in this disorder lack ADP found in dense granules and normally released when platelets are stimulated. This accounts for a poor response to aggregating agents.

Question 27

A fresh blood sample was sent to the laboratory at 8:00am for a PT test. At 15:00, the doctor requested an APTT test to be done on the same sample. What should the technologist do? a. Rerun aPTT on the 8:00am sample and report the results b. Request a new sample for aPTT c. Run aPTT in duplicate and report the average d. Mix the patient plasma with normal plasma and run the aPTT

Answer 27

Request a new sample for aPTT *According to CLSI guidelines, samples for APTT should be centrifuged and tested within 2 hours after collection. However, the sample is stable for 4 hours if stored at 4 ̊C. APTT evaluates the clotting factors in the intrinsic and common pathway, including factors V and VIII, which are necessary for fibrin formation. However, they are both labile. Storage beyond 4 hours causes falsely elevated APTT results. The technologist should request for a new specimen.

Question 28

Platelets interacting with and binding with other platelets is referred to as: a. Adhesion b. Aggregation c. Release d. Retraction

Answer 28

Aggregation *“Adhesion” refers to platelets interacting with something other than platelets. In vivo, platelets adhere to collagen that is exposed when vessel damage occurs. “Aggregation” refers to attachment of platelets to other platelets. Release is the process by which platelet granule contents are secreted. Retraction describes the final steps in coagulation in which the fibrin-platelet plug contracts, restoring normal blood flow to the vessel.

Question 29

Measurement of the time required for fibrin formation when thrombin is added to plasma evaluates the a. Fibrinogen concentration b. Prothrombin concentration c. Extrinsic clotting system d. Intrinsic clotting system

Answer 29

Fibrinogen concentration *When thrombin is added to patient plasma, fibrinogen is converted to fibrin. No factors above fibrinogen in the cascade are measured, including prothrombin. Both the thrombin time and fibrinogen test use thrombin reagent; both tests measure only one factor, fibrinogen.

Question 30

Which platelet surface antigen acts as the receptor for fibrinogen? a. GP Ib/V/IX b. GP IIb/IIIa c. GP Ia/IIa d. GP Ic/IIa

Answer 30

GP IIb/IIIa *GP IIb/IIIa is the platelet membrane receptor that binds fibrinogen and supports platelet aggregation. When platelets are activated, a change in the GP IIb/IIIa receptor allows binding of fibrinogen. Fibrinogen binds to GP IIb/IIIa receptors on adjacent platelets and joins them together in the presence of ionized calcium.

Question 31

Which of the following enzymatically degrades the stabilized fibrin clot? a. Plasminogen b. Plasmin c. Prothrombin d. Thrombin

Answer 31

Plasmin *Plasmin, the active form of plasminogen, is the enzyme responsible for degrading fibrin into several different fragments. The D-dimer test is abnormal when there is excessive fibrinolytic activity. Prothrombin is the inactive precursor of thrombin that cleaves fibrinogen to form fibrin, which is stabilized by the activity of factor XIII.

Question 32

The APTT is sensitive to a deficiency of which clotting factor? a. Factor VII b. Factor X c. PF3 d. Calcium

Answer 32

Factor X *The APTT is sensitive to deficiency of coagulation factors in the intrinsic pathway (factors XII, XI, IX, VIII) and common pathway (X, V, II, and I).

Question 33

Which factor deficiency is associated with a prolonged PT and APTT? a. X b. VIII c. IX d. XI

Answer 33

X Factor X, a common pathway factor deficiency, is most likely suspected, because both PT and APTT are prolonged. Other causes may include liver disease, vitamin K deficiency, and anticoagulant drugs such as Coumadin and heparin.

Question 34

What subendothelial structural protein triggers coagulation through activation of factor VII? a. Thrombomodulin b. Nitric oxide c. Tissue factor d. Thrombin

Answer 34

Tissue factor Coagulation is initiated on tissue-factor bearing cells with the formation of the extrinsic tenase complex TF:VIIa:Ca2+, which activates factors IX and X and produces enough thrombin to activate platelets and factors V, VIII, and XI.

Question 35

Von Willebrand factor mediates platelet adhesion by binding to platelet receptor: a. GP Ib/IIa b. GP Ib/GP IX/GP V c. GP IIb / IIa d. GP Ib/GP IIIa/GP X

Answer 35

GP Ib/GP IX/GP V Adhesion is the property by which platelets bind to nonplatelet surfaces such as subendothelial collagen. VWF binds platelets through their GP Ib/IX/V membrane receptor.

Question 36

What is the most prevalent form of VWD? a. Type 1 b. Type 2A c. Type 2B d. Type 3

Answer 36

Type 1 Type 1 VWD is a quantitative VWF deficiency caused by one of several autosomal dominant frameshifts, nonsense mutations, or deletions that may occur anywhere in the VWF gene. Type 1 comprises 40% to 70% of VWD cases.

Question 37

A defect in GP IIb/IIIa causes: a. Glanzmann thrombasthenia b. Bernard-Soulier syndrome c. Gray platelet syndrome d. Storage pool disease

Answer 37

Glanzmann thrombasthenia *Glanzmann thrombasthenia (GT) is a severe mucocutaneous bleeding disorder caused by amutation in platelet glycoprotein (GP) IIb or IIIa. Normal GP IIb/IIIa recognizes and binds the arginine-glycine-aspatate peptide sequence receptor complex found in fibrinogen and von Willebrand factor.

Question 38

Deficiency on which single factor is likely when the PT result is prolonged and the PTT result is normal? a. Factor V b. Factor VII c. Factor VIII d. Prothrombin

Answer 38

Factor VII Prothrombin time is a test used for extrinsic pathway (factor VII) and common pathway (I, I, V, X). APTT tests the intrinsic and common pathway. Since the PTT test is normal, it can be deducted that the coagulation deficiency is of the extrinsic pathway.

Question 38

Patients with Bernard-Soulier syndrome have which of the following laboratory test findings? a. Abnormal platelet response to arachidonic acid b. Abnormal platelet response to ristocetin c. Abnormal platelet response to collagen d. Thrombocytosis

Answer 38

Abnormal platelet response to ristocetin *BSS platelets have normal aggregation responses to ADP, epinephrine, collagen, and arachidonic acid but do not respond to ristocetin and have diminished response to thrombin. The lack of response to ristocetin is due to the lack of GP Ib/IX/V complexes and the inability of BSS platelets to bind VWF.

Question 38

What is the INR therapeutic range for Coumadin therapy when a patient has a mechanical heart valve? a. 2.0 to 2.5 b. 2 to 3 c. 2.5 to 3.5 d. Coumadin is not indicated for patients with mechanical heart valve

Answer 38

2.5 to 3.5 *The conditions related to INR of 2.5 to 3.5 are mechanical or prosthetic heart valves. DVT, and pulmonary embolism are correlated with an INR of 2.0 to 3.0

Question 39

When the coagulation of fresh whole blood is prevented through the use of an anticoagulant, the straw-colored fluid that can be separated from the cellular elements is a. Serum b. Plasma c. Whole blood d. Platelets

Answer 39

Plasma *Serum and plasma both come from the liquid portion of the blood that remains once the cells are removed. Serum is the liquid that remains after the blood has been clotted. Plasma is the liquid that remains when clotting is prevented with the addition of an anticoagulant.

Question 40

The bevel of the needle should be held______ in the performance of a venipuncture. a. Upwards b. Downwards c. Sideways d. In any direction

Answer 40

Upwards

Question 41

In polycythemia vera, the platelet count is: a. Elevated b. Normal c. Decreased d. Variable

Answer 41

Elevated *Polycythemia vera (PV) is a neoplastic clonal MPN that commonly manifests with panmyelosis in the BM and increases in erythrocytes, granulocytes, and platelets in the peripheral blood. Splenomegaly is common.

Question 42

A hematoma can form if: a. Improper pressure is applied to the site after the venipuncture b. The patient suddenly moves and the needle comes out of the vein c. The needle punctures both walls of the vein d. All of the above

Answer 42

All of the above *A hematoma is a localized collection of extravasated flood, usually clotted, in an organ space or tissue; in skin it gives the appearance of a bruise. It can happen when improper pressure is applied to the site, when a patient suddenly moves and the needle comes out of the vein, and when the needle punctures both walls of the vein.

Question 43

The initiating stimulus to blood coagulation following injury to a blood vessel is: a. Contact activation with collagen b. Vasoconstriction c. Stenosis d. Release of serotonin

Answer 43

Contact activation with collagen *the intrinsic pathway is induced via contact with subendothelial collagen in the presence of HMWK. Collagen is a structural protein of the blood vessel wall, which is normally concealed beneath the cells that line the blood vessel inner walls.

Question 44

Which of the following is not a characteristic of platelets? a. Size of 2 to 4um b. Cytoplasm is light blue with fine red-purple granules c. A discoid shape as an inactive cell d. The presence of a nucleus

Answer 44

The presence of a nucleus *Platelets or thrombocytes have a diameter of 1 to 4um or 2 to 4um with a volume of approximately 6 to 7.5fL and have a discoid shape. With Wright’s stain, platelets have light violet-purple granular appearance and look like “specks of dust”. Platelets lack nucleus. They are cytoplasmic fragments of a blood cell precursor.

Question 45

At all times, approximately ____ of the total number of platelets are in the systemic circulation a. One fourth b. One third c. One half d. Two thirds

Answer 45

Two thirds *At all times approximately two thirds of platelets are seen in the circulation and one third are seen in the spleen.

Question 46

The reference range of platelets in the systemic circulation is: a. 50 to 150 x 109/L b. 100 to 200 x 109/L c. 150 to 350 x 109/L d. 150 to 450 x 109/L

Answer 46

150 to 450 x 109/L *Turgeon: 150 – 400x109/L. Rodak’s: 150 – 450x109/L

Question 47

All of the following are not a characteristic of protein C, except: a. It is a vitamin K-independent zymogen b. It is activated by fibrinogen c. It activates cofactors V and VIII d. Its activity is enhanced by protein S

Answer 47

Its activity is enhanced by protein S *Protein S functions as a cofactor of protein C and as such enchances its activity. Activated protein C inactivates factors Va and VIIIa.

Question 48

In which platelet disorder are the smallest platelets seen? a. May-Hegglin anomaly b. Bernard Soulier syndrome c. Wiskott-Aldrich syndrome d. Gray platelet syndrome

Answer 48

Wiskott-Aldrich syndrome *Wiskott-Aldrich syndrome (WAS) is a blood coagulation disorder characterized by extremely small platelets. There is a risk of bleeding due to thrombocytopenia and small abnormal platelets.

Question 49

The MPV is a. Analogous to the MCHC b. A direct measure of the platelet count c. A measurement of the average volume of platelets d. A comparison of the patient’s value to the normal value

Answer 49

A measurement of the average volume of platelets *The mean platelet volume, analogous to RBC MCV, is also derived from the platelet histogram. Reference values is approximately 7 – 12 fL (Rodak’s) and 6 – 10fL (Turgeon)

Question 50

Alpha granules are found on the platelet in the: a. Peripheral zone b. Sol-gel zone c. Organelle zone d. Membranous systems

Answer 50

Organelle zone *the organelle zone is composed of mitochondria, alpha granules, dense granules, and lysosomes.

Question 51

Platelet store of ADP and ATP are found in: a. Alpha granules b. Dense granules c. Peroxisomes d. Lysosomal granules

Answer 51

Dense granules *The dense granules are composed of (M-CCAPAS): Magnesium, Calcium, Catecholamines, ADP, Pyrophosphate, ATP, Serotonin

Question 52

Endomitosis starts at which specific progenitor? a. MK-I b. BFU-Meg c. LD-CFU-Meg d. MK-III

Answer 52

LD-CFU-Meg *Light density CFU-Meg cannot divide but it retains DNA replication and cytoplasmic maturation for endomitosis. Endomitosis starts with LD-CFU-Meg and ends with MK-II.

Question 53

The least mature specific progenitor a. MK-I b. BFU-Meg c. LD-CFU-Meg d. MK-III

Answer 53

BFU-Meg *The burst forming unit – Meg (BFU-Meg) is the least mature specific progenitor. BFU-Meg is diploid and can perform mitosis.

Question 54

Which of the following is most likely to be abnormal in patients taking aspirin? a. Platelet morphology b. Platelet count c. Bleeding time d. Prothrombin time

Answer 54

Bleeding time *Aspirin is an antiplatelet drug. It prevents platelet aggregation by inhibition of cyclooxygenase. Aspirin has no effect on the platelet count, platelet morphology, or prothrombin time.

Question 55

The number of platelets an average megakaryocyte generates is approximately: a. 25 – 50 b. 40 – 2000 c. 2000 – 4000 d. 20,000 – 40,000

Answer 55

2000 – 4000 *Each megakaryocyte produces approximately 2000 – 4000 platelets. A single megakaryocyte can produce this large number of cells because platelets are nonnucleated fragments of their cytoplasm. Rodak’s = 2000 to 4000. Steininger = 1000 to 4000.

Question 56

The cellular ultrastructure component(s) unique to platelet is/are: a. Cytoplasmic membrane b. Glycocalyx c. Mitochondria d. Microtubules

Answer 56

Glycocalyx *The glycocalyx is found in the peripheral zone and is unique among the cellular components of the blood. It is composed of plasma proteins and carbohydrate molecules that are related to coagulation, complement and fibrinolytic system.

Question 57

This term is derived from Greek meaning “stoppage of blood flow” a. Hemostasis b. Hematopoiesis c. Thrombopoietin d. Erythropoiesis

Answer 57

Hemostasis *Hemostasis is the process that retains the blood within the vascular system during periods of injury, localizes the reaction involved in the site of injury, and repairs and re-establishes blood flow through the injured vessel.

Question 58

It is the largest and most concentrated clotting factor a. Factor I b. Factor II c. Factor III d. Factor IV

Answer 58

Factor I *Factor I or fibrinogen is a large, stable protein synthesized mainly by the liver. Fibrinogen is the ultimate substrate of the coagulation pathway. It is the primary substrate of thrombin.

Question 59

Which of the following has the highest sensitivity? a. ISI = 1 b. ISI > 1 c. ISI < 1 d. AOTA

Answer 59

ISI = 1 *The international sensitivity index (ISI) is used as an exponent in the equation for calculating the international normalized ratio (INR). The ISI is a calibration parameter that defines the responsiveness of the reagent relative to WHO International Reference Preparation, which by definition has an ISI of 1.0. The closer the ISI is to 1, the higher the sensitivity and vice versa.

Question 60

Which of the following may be associated with thrombotic events? a. Decreased Protein C b. Increased fibrinolysis c. Afibrinogenemia d. ITP

Answer 60

Decreased Protein C *Protein C is a physiological inhibitor of coagulation. It is activated by thrombin-thrombomodulin complex. Activated protein C inhibits factors Va and VIIIa. The deficiency of protein C is associated with thrombosis. Increased fibrinolysis, afibrinogenemia, and ITP are all related to bleeding.

Question 61

The most important practice in preventing the spread of disease is: a. Identifying specimens from HIV and HBV patients b. Wearing masks during patient contact c. Proper handwashing d. Wearing disposable laboratory coats

Answer 61

Proper handwashing *Hand contact is the primary method of infection transmission. Handwashing is the best way to break the chain of infection. When hands are visibly soiled, wash hands with soap and water. When hands are not visibly soiled, apply alcohol-based hand-rub (hand sanitizer).

Question 62

Which plasma protein is essential for adhesion? a. Factor VIII b. vWF c. Fibrinogen d. P selectin

Answer 62

vWF *When vascular injury occurs, platelet comes in contact with subendothelium (collagen, fibronectin). vWF binds to glycoprotein Ib/IX/V complex on a platelet surface.

Question 63

The type of nuclear reproduction seen in megakaryocytes is: a. Polypoid division b. Endomitosis c. Meiosis d. Binary fission

Answer 63

Endomitosis Endomitosis is a form of mitosis that lacks telophase and cytokinesis. Endomitosis begins with LD-CFU-Meg and ends with MK-II.

Question 64

The congenital deficiency of Factor IX: a. Hemophilia B b. Christmas disease c. Sex-linked recessive trait d. All of the above

Answer 64

All of the above *Hemophilia B, also known as Christmas disease, is caused by a deficiency in factor IX. It is also sex-linked, markedly heterogenous disorder involving numerous separate mutations resulting in a range of mild to severe bleeding manifestations.

Question 65

All the megakaryocyte progenitor stages resemble ____ and cannot be distinguished by Wright-stained microscopy a. Lymphocyte b. Monocyte c. Neutrophil d. Eosinophil

Answer 65

Lymphocyte *All the three progenitor stages resemble lymphocytes and cannot be distinguished by Wright-stained light microscopy.

Question 66

What is the deficiency in factor XI called? a. Hemophilia C b. Hemophilia B c. Rosenthal syndrome d. Both A and C

Answer 66

Both A and C *Factor XI deficiency is an autosomal dominant hemophilia with mild to moderate bleeding symptoms. More than half of the cases have been described in Ashkenazi Jews, but individuals of any ethnic group may be affected.

Question 67

Most coagulation studies are carried out at what temperature? a. Room temperature b. 4 ̊C c. 37 ̊C d. -20 ̊C

Answer 67

37 ̊C *Most coagulation studies are performed at 37 ̊ C. It is essential, when required, that the specimens and reagents reach the proper temperature of 37 ̊ C before proceeding with the test.

Question 68

Specimens for PT testing may be held at 18 ̊C to 24 ̊ C and tested within ___ hours from the time of collection a. 4 hours b. 24 hours c. 36 hours d. 48 hours

Answer 68

24 hours *Blood samples for PT testing are only acceptable if stored for less than 24 hours at either room temperature or 4 degrees. Prolonged cold storage at 4 degrees Celsius or lower can activate factor VII, which can lead to shortened PT results.

Question 69

Specimens for APTT testing may be held at 18C to 24C and tested within ___ hours from the time of collection a. 4 hours b. 24 hours c. 36 hours d. 48 hours

Answer 69

4 hours *delay in testing of APTT may result in unpredictable changes including the deterioration of the labile factors. If patient is on heparin therapy, samples must be within the lab one hour after draw.

Question 70

The Bethesda assay is used for which determination? a. Heparin induced thrombocytopenia b. Lupus anticoagulant c. Factor VIII inhibitor titer d. Protein S deficiency

Answer 70

Factor VIII inhibitor titer *Quantitation of autoanti-VIII inhibitor is accomplished using the Nijmegen- Bethesda assay, which is ordinarily employed to measure inhibitors in hemophilic patients with alloantibodies to factor VIII.

Question 71

The urea solubility test is specific for detecting deficiencies of factor: a. Factor X b. Factor XI c. Factor XII d. Factor XIII

Answer 71

Factor XIII *Duckert’s test or 5M urea solubility test is a screening test for factor XIII deficiency. The reagent used is 5M urea. Normal clot is insoluble to urea for 24 hours while in factor XIII deficiency, the clot is dissolved in less than 24 hours.

Question 72

It is considered as the most commonly used quality control chart. The date is plotted along the X-axis and the control is represented on Y-axis. a. Levey-Jennings graph b. Youden Twin plot c. CUSUM graph d. Gaussian graph

Answer 72

Levey-Jennings graph *Levey-Jennings chart is a quality control chart used to plot periodic test results for control specimens. Indicates the mean and the 1, 2, and 3 standard deviation intervals on both sides of the mean. The control results are plotted on the y-axis versus time on the x-axis.

Question 73

What test is commonly used to monitor warfarin therapy? a. APTT b. PT c. TT d. INR

Answer 73

INR *The PT is the basis of the international normalized ratio (used) to monitor warfarin/Coumadin anticoagulant therapy and coagulation factor deficiencies and as a diagnostic tool for disorders such as liver disease.

Question 74

A protein that plays a role in both coagulation and platelet aggregation is: a. Factor I b. Factor VIII c. Factor IX d. Factor XI

Answer 74

Factor I *Factor I (fibrinogen) is necessary for platelet aggregation along with the glycoprotein IIb/IIIa complex. Factor I is also a substrate in the common pathway of coagulation. Thrombin acts on fibrinogen to form fibrin clots.

Question 75

Prekallikrein factor: a. Fletcher factor b. Hageman factor c. Stuart-Prower factor d. Stable factor

Answer 75

Fletcher factor *Prekallikrein is otherwise known as Fletcher factor. Prekallikrein is activated to kallikrein that is involved in the early stages of blood clotting.

Question 76

Warfarin is classified as a vitamin K antagonist. The factors that are impacted by warfarin therapy are: a. VIII, IX, X b. I, II, V, and VII c. II, VII, IX, X d. II, V, VII

Answer 76

II, VII, IX, X *Warfarin is a vitamin K antagonist used as an anticoagulant used for treatment and prevention of a variety of coagulopathic and thromboembolic disorders. This would affect the vitamin K dependent factors which are factors IX, X, VII, and II.

Question 77

A patient is suspected of having a factor XIII deficiency. Which test is most likely abnormal? a. Prolonged APTT b. Clot solubility in a 5M urea solution c. Euglobulin clot lysis d. Prolonged PT

Answer 77

Clot solubility in a 5M urea solution *Duckert’s test or 5M urea solubility test is a screening test for factor XIII deficiency. The reagent used is 5M urea. Normal clot is insoluble to urea for 24 hours while in factor XIII deficiency, the clot is dissolved in less than 24 hours.

Question 78

When viewing platelet morphology on a blood smear, the presence of giant platelets is noted. This may indicate: a. Bernard-Soulier syndrome b. Von Willebrand disease c. Glanzmann thrombasthenia d. Ehler-Danlos disease

Answer 78

Bernard-Soulier syndrome *Bernard-Soulier syndrome is a disorder characterized by the largest platelets seen in a platelet disorder.

Question 79

Patients with Wiskott-Aldrich syndrome present with: a. Eczema b. Thrombocytopenia c. Small platelets d. All of the above

Answer 79

All of the above Wiskott-Aldrich is characterized by the triad of: eczema, thrombocytopenia with smallest platelets seen, and immunodeficiency.

Question 80

Hemophilia B is a sex-linked recessive disorder that presents with a decrease in factor: a. VIII b. IX c. X d. XI

Answer 80

IX *Hemophilia B or Christmas disease is an X-linked recessive anatomic bleeding disorder caused by a deficiency in coagulation factor IX.

Question 81

The activation of plasminogen to plasmin resulting in the degradation of fibrin occurs by: a. PAI-1 b. Alpha-2 antiplasmin c. tPA d. alpha-2 macroglobulin

Answer 81

tPA *tissue plasminogen activator is a substance that cleaves plasminogen and converts it to plasmin, thus initiating fibrinolysis.

Question 82

which of the following characteristics are common between Hermansky-Pudlak and Chediak-Higashi syndromes? a. Giant inclusion granules in granulocytes b. Alpha granules storage pool defects c. Inclusions in macrophages d. Oculocutaneous albinism

Answer 82

Oculocutaneous albinism *Hermansky-Pudlak syndrome is a dense granule deficiency that is an autosomal recessive disorder characterized by tyrosinase- positive oculocutaneous albinism. Chediak-Higashi syndrome is a rare autosomal recessive disorder characterized by partial oculocutaneous albinism, frequent pyogenic bacterial infections, and giant lysosomal granules.

Question 83

The platelet disorder in which the abnormality is due to a defect in platelet aggregation is: a. Glanzmann thrombasthenia b. Von Willebrand disease c. Storage pool disease d. Bernard-Soulier syndrome

Answer 83

Glanzmann thrombasthenia *Glanzmann thrombasthenia is caused by the lack of expression of GP IIb/IIIa complexes on the platelet surface. This complex is known as the platelet aggregation receptor, and its absence is associated with a severe bleeding disorder.

Question 84

Swelling of tumor in the tissue of a body cavity that contains clotted blood. a. Ecchymosis b. Hematoma c. Purpura d. Petechiae

Answer 84

Hematoma *Hematoma results when leakage of a large amount of blood around the puncture site causes the area to rapidly swell (Rodak’s)

Question 85

Form of purpura in which blood escapes into large areas of skin and mucous membranes, but not into deep tissues. They are usually irregular in shape. a. Ecchymosis b. Hematoma c. Purpura d. Petechiae

Answer 85

Ecchymosis *Ecchymosis is caused by a leakage of a small amount of blood on the tissue around the puncture site. Size is usually larger than 1cm.

Question 86

Nosebleed that lasts longer than 10 minutes: a. Hemarthrosis b. Hematemesis c. Epistaxis d. Melena

Answer 86

Epistaxis *Epistaxis is a nosebleed that is recurrent, bleeding from both nostrils, lasts longer than 10 minutes, or require physical intervention.

Question 87

Hyperextended or hypermobile joints and hyperplastic skin: a. Kasabach-Meritt syndrome b. Ehlers Danlos syndrome c. Marfan syndrome d. Osler-Weber-Rendu syndrome

Answer 87

Ehlers Danlos syndrome *Ehlers Danlos syndrome may be transmitted as autosomal dominant, recessive, or X-linked trait. It is manifested by hyperextensible skin, hypermobile joints, joint laxity, fragile tissues, and a bleeding tendency.

Question 88

What are the fibrinogen levels in Hemophilia A, B, and C, respectively? a. Increased, increased, increased b. Normal, normal, normal c. Decreased, decreased, decreased d. Increased, decreased, increased

Answer 88

Normal, normal, normal *Hemophilia is usually an inherited bleeding disorder in which does not clot properly. Hemophilia A, B, and C are specific clotting factor deficiencies and are not associated with the increase or decrease of fibrinogen.

Question 89

In which of the following is the demarcation system present? a. MK-I b. MK-II c. MK-III d. All of the above

Answer 89

All of the above *The demarcation system (DMS) in megakaryocytes forms the plasma membrane (PM) of future platelets. The demarcation system is present among all platelet precursors (MK-I, MK-II, and MK-III).

Question 90

It forms the cytoskeleton of the platelet a. Peripheral zone b. Sol-gel sone c. Organelle zone d. Membranous system

Answer 90

Sol-gel sone *The sol-gel zone forms the cytoskeleton of the platelet. It is composed of microfilaments (actin and myosin), intermediate filaments (desmin and vimentin), and microtubules (tubulin). It provides the structure for maintaining the circulating discoid shape of the cell, and also maintains the position of the organelles.

Question 91

What is the usual shape of platelets in citrated blood? a. Cylindrical and beaded b. Biconvex and discoid c. Spherical or round with pseudopods d. Round

Answer 91

Cylindrical and beaded *In citrated blood, platelets are cylindrical and beaded that resembles fragments of megakaryocyte proplatelet. Inactive platelets are biconvex and discoid while activated platelets are usually spherical or round with pseudopods. In EDTA, platelets are round.

Question 92

All are terms that refer to Fitzgerald factor, except: a. Contact activation cofactor b. William’s factor c. Laki-Lorand factor d. None of the above

Answer 92

Laki-Lorand factor *Fitzgerald factor or High Molecular Weight Kininogen (HMWK) is also known as Contact activation factor, William’s factor, and Flaujeac factor. Laki-Lorand factor is another term for factor XIII (Fibrin stabilizing factor).

Question 93

Which is the primary inhibitor of plasmin? a. Thrombospondin b. Alpha-2 antiplasmin c. Alpha-2 macroglobulin d. PAI-1

Answer 93

Alpha-2 antiplasmin *Alpha-2 antiplasmin is the primary inhibitor of plasmin. Alpha-2 antiplasmin binds noncovalently to the lysine binding iste of plasminogen, competitively inhibiting binding of plasminogen to fibrin.

Question 94

A specimen supposedly tested for coagulation has been stored in a 4C refrigerator. Which of the following factors will be prematurely activated? a. I and II b. III and V c. VII and IX d. VII and XI

Answer 94

VII and XI *Factors VII and XI prematurely activates when placed at a cold temperature (4C). Mnemonic: Malamig (cold) sa 7/11.

Question 95

A platelet-poor plasma should contain how many platelets? a. Less than 10,000/uL b. More than 10,000/uL c. More than 200,000/uL d. Less than 200,000/uL

Answer 95

Less than 10,000/uL *Platelet poor plasma (PPP) can be obtained by centrifuging whole blood collected from 3.2% sodium citrate at 1500g x for 15 minutes. It contains less than 10,000/uL platelets and is used for clot-based coagulation test (e.g. PT and APTT)

Question 96

What is the platelet if the platelet is reported as “slightly decreased”? a. 200,000 to 400,000 b. 150,000 to 199,000 c. 100,000 to 149,000 d. 50,000 to 99,000

Answer 96

100,000 to 149,000 *In platelet estimate, a slightly decreased platelet report correlates to a platelet estimate of 100,000 to 149,000 platelets/uL.

Question 97

D-dimer test is positive in DIC as soon as ___after onset. a. 4 minutes b. 4 hours c. 8 hours d. 8 minutes

Answer 97

4 hours *Presence of crosslinked D -dimer indicates that a stable fibrin clot has been lysed and will be found in the pulmonary embolism, deep vein thrombosis, DIC with secondary fibrinolysis and sickle cell disease. D-dimer test is positive as soon as 4 hours after onset. Fibrinogen levels may decrease in 4 to 24 hours, platelets decrease up to 48 hours after onset.

Question 98

The hemorrhagic problems associated with scurvy are due to a deficiency of ______. a. Vitamin C b. Prothrombin c. Vitamin K d. Protein C

Answer 98

Protein C *Vascular integrity is influenced by vitamin C intake. In a deficiency or absence of vitamin C, collagen production is insufficient or abnormal. Vitamin C deficiency is associated with capillary fragility and the primary hemostasis bleeding symptoms of petechiae and mucosal bleeding.