Thrombostasis

Question 1

Describe in 4 steps the process of primary hemostasis

Answer 1

1. transient vasoconstriction - endothelin
2. adhesion: GpIb to vWF to collagen on endothelium
3. degranulation:
   -ADP –> exposure of GPIIB/IIIa
   -TXA2 by COX - promotes aggregation
4. aggregation:
   GPIIb/IIIa to fibrinogen

Question 2

What are the clinical findings of primary hemostasis disorders?

Answer 2

mucosal and skin bleeding:

• GI, epistaxis, hemoptysis, hematuria, menorrhagia
• petechiae
• severe: intracranial hemorrhage

Question 3

What is the most common cause of thrombocytopenia in both children and adults?

Answer 3

immune thrombocytopenic purpura

Question 4

What drug can cause induced thrombocytopenia via igG

Answer 4

heparin

Question 5

What is the cause of TTP?

Answer 5

dec ADMNTS13 - enzyme that normally cleaves vWF

-due to acquired autoantibody

Question 6

What bacteria is infamous for causing HUS?

Answer 6

Ecoli - verotoxin damages endothelial cells

Question 7

Is renal insufficiency or CNS insufficiency more common in TTP? HUS?

Answer 7

TTP: CNS
HUS: Renal

Question 8

What is the effect on PT/PTT in HUS and TTP?

Answer 8

NONE

-no effect on coagulation cascade

Question 9

What is wiskott aldrich syndrome?

Answer 9

affected boys have small platelets, eczema, immunodeficiency

Question 10

What antigen can cause neonatal alloimmune thrombocytopenia?

Answer 10

HPA1a

Question 11

Name the genetic defect and result:

-Bernard soulier syndrome

Answer 11

GPIb deficiency

• adhesion is impaired
• mild thrombocytopenia, enlarged platelets

Big Suckers

Question 12

Name the genetic defect and result:

-glanzman thrombasthenia

Answer 12

GPIIB/IIIa deficiency

• aggregation is impaired
• normal platelet count

Question 13

Who does purpura simplex affect?

Answer 13

women during menses

-purpuric spots of dermis

Question 14

What are four causes of thrombocytosis?

Answer 14

1. iron deficiency anemia
2. splenectomy
3. cancer
4. chronic inflammatory disorder

Question 15

What is the goal of secondary hemostasis?

Answer 15

• stabilizes the weak platelet plug

- thrombin converts fibrinogen –> fibrin

Question 16

What are some clinical features of secondary hemostasis disorders?

Answer 16

• deep tissue bleeding into muscle and joints

- rebleeding after surgical procedures

Question 17

What pathways does PT/PTT measure?

Answer 17

PT: extrinsic and common
PTT: intrinsic and common

Question 18

Describe the intrinsic pathway?

Answer 18

subendothelial collagen –> 12–>11–>9–>8

Question 19

What drug affects the intrinsic pathway?

Answer 19

heparin

Question 20

Describe the extrinsic pathway?

Answer 20

tissue thromboplastin–> 7

Question 21

What drug affects the extrinsic pathway?

Answer 21

coumadin

Question 22

Describe the common pathway

Answer 22

fibrinogen –> 5, 2, 1

Question 23

What factor is deficient in hemophilia A? what is the result

Answer 23

factor VIII

• inc PTT
• deep tissue bleeding

Question 24

What factor is deficient in christmas or hemophilia B

Answer 24

factor IX

Question 25

What is the most common acquired autoantibody against a coagulation factor

Answer 25

vIII and then vWF

Question 26

in a mixing study, would PTT be corrected for patients with hemophilia A or patients with a coagulation inhibitor autoantibody?

Answer 26

ONLY hemophilia A | -coagulation inhibitor would block factor VIII still and PTT would remain inc

Question 27

What is the most common inherited coagulation disorder?

Answer 27

vWF deficiency - autosomal dominant

Question 28

in vWF disease, is PT , PTT, or neither increased?

Answer 28

PTT is increased - vWF is needed to stabilize factor VIII - intrinsic pathway

Question 29

What test diagnoses vWF disease?

Answer 29

Ristocetin test - induces platelet agglutination - lack of agglutination diagnoses vWF disease

Question 30

How is vWF disease treated?

Answer 30

desmopressin - induces vWF release from weibel palade bodies

Question 31

What factors does vitamin K deficiency disrupt

Answer 31

2, 7, 9, 10 protein C and S

Question 32

Describe the pathology of DIC

Answer 32

procoagulant TF is released after injury and inappropriately activates factor 12

Question 33

What are five situations in which DIC is likely?

Answer 33

1. obstretic complication - thromboplastin in amniotic fluid 2. Ecoli or N meningitis 3. adenocarcinoma - mucin 4. APL - primary granules 5. rattle snake bite

Question 34

What are some lab findings in DIC

Answer 34

1. dec platelet 2. inc PT and PTT - consumption of clotting factors 3. dec fibrinogen 4. elevated fibrin split products - D-dimer - THIS result is most sensitive 5. shistocytes

Question 35

What are two conditions that can cause disorders of fibrinolysis and why?

Answer 35

1. radical prostatectomy - urokinase - actvates plasmin | 2. cirrhosis of the liver - reduced alpha 2 antiplasmin

Question 36

What are the lab findings in a fibrinolysis disorder?

Answer 36

1. inc PT/PTT 2. inc bleeding time 3. inc fibrinogen split products - NOT d dimer

Question 37

what are some things that are released when endothelial cells are damaged that lead to thrombosis?

Answer 37

1. NO and prostacyclin 2. heparin like molecules - block anti thrombin III 3. TPA 4. thrombomodulin

Question 38

When heparin is initially given which factors are relatively deficient?

Answer 38

protein c and s

Question 39

What do protein C and S normally inactivate?

Answer 39

factor V and VIII - amplifying factors

Question 40

What is the most common cause of inherited hypercoaguable state?

Answer 40

factor V leiden - lacks cleavage site for deactivation by protein C and S

Question 41

What lab test indicates antiIII deficiency?

Answer 41

PTT does not rise with heparin