Thrombostasis Flashcards

1
Q

Describe in 4 steps the process of primary hemostasis

A
  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
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2
Q

What are the clinical findings of primary hemostasis disorders?

A

mucosal and skin bleeding:

  • GI, epistaxis, hemoptysis, hematuria, menorrhagia
  • petechiae
  • severe: intracranial hemorrhage
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3
Q

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

A

immune thrombocytopenic purpura

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4
Q

What drug can cause induced thrombocytopenia via igG

A

heparin

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5
Q

What is the cause of TTP?

A

dec ADMNTS13 - enzyme that normally cleaves vWF

-due to acquired autoantibody

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6
Q

What bacteria is infamous for causing HUS?

A

Ecoli - verotoxin damages endothelial cells

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7
Q

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

A

TTP: CNS
HUS: Renal

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8
Q

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

A

NONE

-no effect on coagulation cascade

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9
Q

What is wiskott aldrich syndrome?

A

affected boys have small platelets, eczema, immunodeficiency

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10
Q

What antigen can cause neonatal alloimmune thrombocytopenia?

A

HPA1a

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11
Q

Name the genetic defect and result:

-Bernard soulier syndrome

A

GPIb deficiency

  • adhesion is impaired
  • mild thrombocytopenia, enlarged platelets

Big Suckers

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12
Q

Name the genetic defect and result:

-glanzman thrombasthenia

A

GPIIB/IIIa deficiency

  • aggregation is impaired
  • normal platelet count
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13
Q

Who does purpura simplex affect?

A

women during menses

-purpuric spots of dermis

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14
Q

What are four causes of thrombocytosis?

A
  1. iron deficiency anemia
  2. splenectomy
  3. cancer
  4. chronic inflammatory disorder
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15
Q

What is the goal of secondary hemostasis?

A
  • stabilizes the weak platelet plug

- thrombin converts fibrinogen –> fibrin

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16
Q

What are some clinical features of secondary hemostasis disorders?

A
  • deep tissue bleeding into muscle and joints

- rebleeding after surgical procedures

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17
Q

What pathways does PT/PTT measure?

A

PT: extrinsic and common
PTT: intrinsic and common

18
Q

Describe the intrinsic pathway?

A

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

19
Q

What drug affects the intrinsic pathway?

A

heparin

20
Q

Describe the extrinsic pathway?

A

tissue thromboplastin–> 7

21
Q

What drug affects the extrinsic pathway?

A

coumadin

22
Q

Describe the common pathway

A

fibrinogen –> 5, 2, 1

23
Q

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

A

factor VIII

  • inc PTT
  • deep tissue bleeding
24
Q

What factor is deficient in christmas or hemophilia B

A

factor IX

25
Q

What is the most common acquired autoantibody against a coagulation factor

A

vIII and then vWF

26
Q

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

A

ONLY hemophilia A

-coagulation inhibitor would block factor VIII still and PTT would remain inc

27
Q

What is the most common inherited coagulation disorder?

A

vWF deficiency - autosomal dominant

28
Q

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

A

PTT is increased

  • vWF is needed to stabilize factor VIII
  • intrinsic pathway
29
Q

What test diagnoses vWF disease?

A

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

30
Q

How is vWF disease treated?

A

desmopressin - induces vWF release from weibel palade bodies

31
Q

What factors does vitamin K deficiency disrupt

A

2, 7, 9, 10 protein C and S

32
Q

Describe the pathology of DIC

A

procoagulant TF is released after injury and inappropriately activates factor 12

33
Q

What are five situations in which DIC is likely?

A
  1. obstretic complication - thromboplastin in amniotic fluid
  2. Ecoli or N meningitis
  3. adenocarcinoma - mucin
  4. APL - primary granules
  5. rattle snake bite
34
Q

What are some lab findings in DIC

A
  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
35
Q

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

A
  1. radical prostatectomy - urokinase - actvates plasmin

2. cirrhosis of the liver - reduced alpha 2 antiplasmin

36
Q

What are the lab findings in a fibrinolysis disorder?

A
  1. inc PT/PTT
  2. inc bleeding time
  3. inc fibrinogen split products - NOT d dimer
37
Q

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

A
  1. NO and prostacyclin
  2. heparin like molecules - block anti thrombin III
  3. TPA
  4. thrombomodulin
38
Q

When heparin is initially given which factors are relatively deficient?

A

protein c and s

39
Q

What do protein C and S normally inactivate?

A

factor V and VIII - amplifying factors

40
Q

What is the most common cause of inherited hypercoaguable state?

A

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

41
Q

What lab test indicates antiIII deficiency?

A

PTT does not rise with heparin