2.2 Platelet and Vascular Disorders

Question 1

Thrombotic thrombocytopenic purpura (TTP) is characterized by:
A. Prolonged PT
B. Increased PLT aggregation
C. Thrombocytosis
D. Prolonged APTT

Answer 1

B. Increased PLT aggregation

Question 2

Thrombocytopenia may be associated with:
A. Splenectomy
B. Hypersplenism
C. Acute blood loss
D. Increased proliferation of pluripotent stem cells

Answer 2

B. Hypersplenism

Question 3

Aspirin prevents PLT aggregation by inhibiting the action of which enzyme?
A. Phospholipase
B. Cyclo-oxygenase
C. Thromboxane A2 (TXA2) synthetase
D. Prostacyclin synthetase

Answer 3

B. Cyclo-oxygenase

Question 4

Normal PLT adhesion depends on:
A. Fibrinogen
B. Glycoprotein Ib
C. Glycoprotein IIb–IIIa complex
D. Calcium

Answer 4

B. Glycoprotein Ib

Question 5

Which of the following test results is normal in a patient with classic von Willebrand disease?
A. PLT aggregation
B. APTT
C. PLT count
D. Factor VIII:C and von Willebrand factor (VWF) levels

Answer 5

C. PLT count

Question 6

Bernard–Soulier syndrome is associated with:
A. Decreased factor IX
B. Decreased factor VIII
C. Thrombocytopenia and giant PLTs
D. Abnormal PLT function test results

Answer 6

C. Thrombocytopenia and giant PLTs

Question 7

When performing PLT aggregation studies, which set of PLT aggregation results would most likely be associated with Bernard–Soulier syndrome?
A. Normal PLT aggregation to collagen, adenosine diphosphate (ADP), and ristocetin
B. Normal PLT aggregation to collagen, ADP, and epinephrine (EPI); decreased aggregation to ristocetin
C. Normal PLT aggregation to EPI and ristocetin; decreased aggregation to collagen and ADP
D. Normal PLT aggregation to EPI, ristocetin, and collagen; decreased aggregation to ADP

Answer 7

B. Normal PLT aggregation to collagen, ADP, and epinephrine (EPI); decreased aggregation to ristocetin

Question 8

Which set of PLT responses would be most likely associated with Glanzmann thrombasthenia?
A. Normal PLT aggregation to ADP and ristocetin; decreased aggregation to collagen
B. Normal PLT aggregation to collagen; decreased aggregation to ADP and ristocetin
C. Normal PLT aggregation to ristocetin; decreased aggregation to collagen, ADP, and EPI
D. Normal PLT aggregation to ADP; decreased aggregation to collagen and ristocetin

Answer 8

C. Normal PLT aggregation to ristocetin; decreased aggregation to collagen, ADP, and EPI

Question 9

Which of the following is a characteristic of acute immune thrombocytopenic purpura?
A. Spontaneous remission within a few weeks
B. Predominantly seen in adults
C. Nonimmune PLT destruction
D. Insidious onset

Answer 9

A. Spontaneous remission within a few weeks

Question 10

TTP differs from DIC in that:
A. APTT is normal in TTP but prolonged in DIC
B. Schistocytes are not present in TTP but are present in DIC
C. PLT count is decreased in TTP but normal in DIC
D. PT is prolonged in TTP but decreased in DIC

Answer 10

A. APTT is normal in TTP but prolonged in DIC

Question 11

Several hours after birth, a baby boy develops petechiae and purpura and hemorrhagic diathesis. The PLT count is 18 × 109/L. What is the most likely explanation for the low PLT count?
A. Drug-induced thrombocytopenia
B. Secondary thrombocytopenia
C. Neonatal alloimmune thrombocytopenia
D. Neonatal DIC

Answer 11

C. Neonatal alloimmune thrombocytopenia

Question 12

Which of the following is associated with post-transfusion purpura (PTP)?
A. Nonimmune thrombocytopenia/alloantibodies
B. Immune-mediated thrombocytopenia/alloantibodies
C. Immune-mediated thrombocytopenia/autoantibodies
D. Nonimmune-mediated thrombocytopenia/autoantibodies

Answer 12

B. Immune-mediated thrombocytopenia/alloantibodies

Question 13

Hemolytic uremic syndrome (HUS) is associated with:
A. Fever, thrombocytosis, anemia, and renal failure
B. Fever, granulocytosis, and thrombocytosis
C. Escherichia coli 0157:H7
D. Leukocytosis and thrombocytosis

Answer 13

C. Escherichia coli 0157:H7

Question 14

Storage pool deficiencies are defects of:
A. PLT adhesion
B. PLT aggregation
C. PLT granules
D. PLT production

Answer 14

C. PLT granules

Question 15

Lumi-aggregation measures:
A. PLT aggregation only
B. PLT aggregation and adenosine triphosphate (ATP) release
C. PLT adhesion
D. PLT glycoprotein Ib

Answer 15

B. PLT aggregation and adenosine triphosphate (ATP) release

Question 16

Neurological findings may be commonly associated with which of the following disorders?
A. HUS
B. TTP
C. ITP
D. PTP

Answer 16

B. TTP

Question 17

Which of the following is correct regarding acquired TTP?
A. Autoimmune disease
B. Decreased VWF
C. Decreased PLT aggregation
D. Decreased PLT adhesion

Answer 17

A. Autoimmune disease

Question 18

Hereditary hemorrhagic telangiectasia is a disorder of:
A. PLTs
B. Clotting proteins
C. Fibrinolysis
D. Connective tissue

Answer 18

D. Connective tissue

Question 19

Which of the following prevents PLT aggregation?
A. TXA2
B. Thromboxane B2
C. Prostacyclin
D. Antithrombin (AT)

Answer 19

C. Prostacyclin

Question 20

Which defect characterizes Gray syndrome?
A. PLT adhesion defect
B. Dense granule defect
C. Alpha granule defect
D. Coagulation defect

Answer 20

C. Alpha granule defect

Question 21

The P2Y12 ADP receptor agonist assay may be used to monitor PLT aggregation inhibition to which of the following drugs?
A. Warfarin
B. Heparin
C. Low-molecular-weight heparin (LMWH)
D. Clopidogrel (Plavix)

Answer 21

D. Clopidogrel (Plavix)

Question 22

Which of the following instruments can be used to evaluate PLT function?
A. PLT aggregometer
B. VerifyNow
C. PFA-100
D. All of the above

Answer 22

D. All of the above

Question 23

Which of the following PLT aggregating agents demonstrates a monophasic aggregation curve when used in the optimal concentration?
A. Thrombin
B. Collagen
C. ADP
D. EPI

Answer 23

B. Collagen