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Pathoma > Chapter 4: Hemostasis And Related Disorders > Flashcards

Chapter 4: Hemostasis And Related Disorders Flashcards

1
Q

Formation of weak platelet plug mediated between interaction btw platelets and endothelium

A

Primary Hemostasis

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2
Q

Strengthening of weak platelet plug via coagulation cascade

A

Secondary Hemostatsis

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3
Q

What are the 4 steps of Primary Hemostatsis

A

Transient vasoconstriction
Platelet Adhesion
Platelet degranulation
Platelet aggregation

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4
Q

What 2 processes mediate transient vasoconstriction

A

Neural Reflex

Release of ENDOTHELIN from damage cells

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5
Q

Before platelets can bind, what molecule must interact with exposed collagen on the damaged endothelium

A

vWF !

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6
Q

where if vWF produced in the body

A

Alpha granules of platelets

Weibel Palade Bodies of the endothelium

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7
Q

Once vWF is bound to exposed to collagen what receptor on platelets interacts with vWF ?

A

Gp1B

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8
Q

What other important adhesion molecule is made in the Weibel Palade bodies besides vWF ?

A

P-selectin (used in rolling of WBC)

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9
Q

Upon interation of vWF to Gp1b what occurs ?

A

Platelet Degranulation

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10
Q

What two products are released by platelet degranulation

A

ADP

TxA2

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11
Q

ADP causes the up regulation of which protein on platelets ?

A

GpIIB/IIIA receptor

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12
Q

TxA2 has what effect ?

A

Increases platelet aggregation

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13
Q

What enzyme makes TxA2 ?

A

COX (platelet)

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14
Q

What is the function of GpIIB/IIIA receptor ?

A

Platelet aggregation

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15
Q

What does GpIIB/IIIA receptor bind to ?

A

Fibrinogen (linker protein between two platelets)

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16
Q

Quantitative primary hemostasis disorder are due to …

A

NOT ENOUGH PLATELETS (Thrombocytopenia)

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17
Q

Qualitative primary hemostasis disorder are due to …

A

Defective Platelets

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18
Q

What are common symptoms of primary hemostasis disorders ?

A 
SKIN BLEEDING 
Mucosal bleeding:
   Epistaxis
   GI bleeding 
   Intracranial bleeding (Thrombocytopenia)
   Hemoptysis
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19
Q

Petechiae

A

1-2 mm lesions of skin bleeding

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20
Q

Purpura

A

3mm or greater lesions of skin bleeding

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21
Q

Ecchymoses

A

Greater than 1cm lesion of skin bleeding

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22
Q

Normal level of platelets

A

150-400 K/uL

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23
Q

Level at which symptoms of thrombocytopeina are notices

A

<50K/ uL

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24
Q

Normal bleeding time

A

2-7 minutes

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25
Q

Is bleeding time affected by disorders of primary hemostasis ?

A

YES (elevated)

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26
Q

Immune Thrombocytopenic Purpura (ITP) is due to what type of Ig directed at platelets ?

A

IgG (often to GpIIB/IIIA)

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27
Q

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

A

ITP !

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28
Q

Where are the Ab’s to platelets produced in the body ?

A

Plasma Cells in the SPLEEN !

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29
Q

What occurs that leads to thrombocytopenia in ITP ?

A

Platelets are brought to the spleen and destroyed by macrophages

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30
Q

The acute form of ITP occurs in CHILDREN and is preceded by what event ?

A

Viral infections or Immunizations (weeks prior)

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31
Q

What is the prognosis for Acute ITP ?

A

WIll resolve in weeks after presentation.

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32
Q

In which patients is Chronic ITP most likely ?

A

Pregnant Women and those with Auto Immune Disease such as Lupus.

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33
Q

What may occur in fetus/neonates who are born to mothers with Chronic ITP ?

A

Short lived ITP due to crossing of IgG through the Placenta

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34
Q

What would you expect to see of the lab values for Bleeding Time , PT, PTT and Megakaryocyte counts in ITP ?

A

Bleeding time increased
PT and PTT normal (No effect on coagulation cascade)
Increased megakaryocytic (to make up for platelets being destroyed)

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35
Q

What is the initially treatment for ITP

A

Corticosteroids (dial down the immune response)

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36
Q

How does IV IgG help in ITP ?

A

Give another substrate for the macrophages in the spleen to latch onto (dilution principle)

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37
Q

What is the treatment for refractory cases of ITP ?

A

Splenectomy (remove the spleen, remove the sours of destruction/Ab production)

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38
Q

In Microangiopathic Thrombocytopenic Purpura (MTP), what occurs that leads to low platelets ?

A

Consumption of platelets due to the formation of micro thrombi in small blood vessels

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39
Q

Why are schistocytes/anemia formed in MTP ?

A

The micro thrombi stack up in the small vessels and as the RBC’s try to get by they are damaged –> Schistocytes. Schistocytes are removed in the spleen by splenic macrophages.

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40
Q

What are the two main diseases associated with MTP ?

A

Thrombotic Thrombocytopenic Purpura (TTP)

Hemolytic Uremic Syndrome (HUS)

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41
Q

What occurs in TTP that leads to micro thrombi formation and thrombocytopenia ?

A

A decrease in ADAMTS13 levels –> Microthrombi production

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42
Q

What is the function of ADAMTS13 ?

A

Cleaves vWF to inactivate it so that there can be resolution of clotting

In low ADAMTS13, vWF is not cleaved leading to increased thrombi formation and platelet exhaustion –> thrombocytopenia

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43
Q

What is the cause for low ADAMTS13 ?

A

Antibody to it !

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44
Q

What leads to the formation of microthrombis in HUS ?

A

Damage to the endothelium by drugs or infection

Mainly associated with children who are infected with E.coli O157:H7

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45
Q

How does E.coli O157:H7 damage endothelium ?

A

Production fo E.coli verotoxin

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46
Q

Both HUS and TTP present with skin/mucosal bleeding, hemolytic anemia, and fever. Which of the two is more associated with CNS abnormalities ?

A

TTP

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47
Q

Both HUS and TTP present with skin/mucosal bleeding, hemolytic anemia, and fever. Which of the two is more associated with Renal insufficiency?

A

HUS

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48
Q

Will bleeding time be increased in MTP ?

A

Yes

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49
Q

What would you expect of the PT/PTT in MTP ?

A

Normal (no effect on clotting cascade)

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50
Q

Will the number of megakaryocytes be increased or decreased in MTP ?

A

Increased

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51
Q

What are the two main treatments for MTP ?

A

Plamaphoresis and Corticosteroids.

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52
Q

Bernadr-Soulier is due to a gentic defect in which receptor ?

A

Gp1B (binds to vWF)

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53
Q

What would you see on blood smears for Bernard-Soulier ?

A

Thrombocytopenia and enlarged platelets (BS = Big Suckers)

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54
Q

Glanzmann Thrombocyopenia is due to a defect in which receptor ?

A

GpIIB/IIIA (Limited platelet aggregation)

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55
Q

How does Aspirin affect platelet aggregation /

A

Decreases the amount of TxA2 produced by inhibiting COX irreversibly.

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56
Q

What does Uremia disrupt that causes platelet disorders ?

A

Inhibits platelet adhesion and aggregation

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57
Q

What is the main end product of the coagulation cascade ?

A

Thrombin

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58
Q

What is the role of Thrombin ?

A

Cleaves fibrinogen to fibrin allowing for cross linking and stabilization of clot

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59
Q

Where are the factors of the clotting cascade produced ?

A

Liver (liver disease may lead to increased bleeding)

60
Q

What clotting factors are associated with the Inctrinsic Pathway ?

A

12, 11,9,8 –> activation of factor 10

61
Q

What clotting factors are associated with the extrinsic pathway ?

A

7 –> activation of factor 10

62
Q

What clotting factors are associated with the common pathway ?

A

10, 5,2,1 (Firbrinogen)

2 is prothrombin
1 is fibrinognen

63
Q

What leads to the activation of Factor XII (starting point of the intrinsic pathway) ?

A

Subendothelial Collagen

64
Q

What leads to the Activation of Factor VII (starting point of the extrinsic pathway) ?

A

Tissue THromboplastin

65
Q

What is a major sign of Secondary Hemostasis Disorders ?

A

Deep tissue bleeding into muscles and joint (hemarthrosis) and rebreeding after surgical procedures

66
Q

What test is used for the intrinsic pathway ?

A

PTT (Factor XII,XI, IX, VIII and common factors)

67
Q

What test is used for extrinsic Pathway ?

A

PT (Factor VII and common pathway)

68
Q

Hemophilia A is a X-linked Recessive trait (can come on from spontaneous mutation) in what gene ?

A

Clotting Factor VIII (A for 8)

69
Q

What would you expect to see on PTT for Hemophilia A ? PT

A

Increased PTT
No Change for PT

Reason: Factor VIII is in the Intrinsic pathway.

70
Q

What would the Bleeding Time be in Hemophilia A ?

A

NORMAL (normal platelet count too)

71
Q

Treatment for Hemophilia A

A

Recombinant Factor VIII

72
Q

Hemophilia B is due to a mutation in which clotting factor ?

A

Factor IX

73
Q

PTT and PT in Hemophilia B ?

A

Increased and Normal respectively (extrinsic is not affected)

74
Q

Presentation for Hemophilia B ?

A

Same as for A (Hemarthrosis and post surgical bleeding)

75
Q

What is the most common Coagulation Factor that is inhibited by Ab produced against it ?

A

Factor VIII !

Presents like Hemophilia A

76
Q

How can you differentiate between Hemophilia A and Factor VIII inhibitor disease ?

A

Mix the blood with Normal Serum”

In Hemophilia A the PTT will correct due to increased factor VIII

In Factor VIII inhibitor disease, it will not since the inhibitor will still neutralize the Factor VIII

77
Q

What is THE MOST COMMON inherited coagulation disorder ?

A

von Willebrands Disease

78
Q

Describe the etiology of Von willebrands disease

A

AUtosomal Dominant disorder leading to decreased vWF

79
Q

Why would you see and altered Bleeding Time and PTT in Von Willebrands Disease ?

A

Bleeding Time increases due to lack of vWF

PTT increases because vWF STABILIZES factor VIII in the blood. Without sufficient vWF factor VIII will be decreased leading to increased PTT.

80
Q

What is Risocetin and how can it be used to test for von Willebrands Disease ?

A

Risocetin iduces platelet aggregation which occurs after vWF binding Gp1B. If risocetin is admin and there is still no change then that is suspicious for vWD

81
Q

Quick Quiz: What drugs efficacy is being measured by PT ?

A

Warfarin

82
Q

Quick Quiz: What drugs efficacy is being measured by PTT?

A

Heparin

83
Q

What is the treatment for vWD ?

A

Desmopressin

ADH analog –> increased vWF release.

84
Q

Where in the body is epoxide reductase located (enzyme that activates Vitamin K) ?

A

Liver

85
Q

What clotting factors are need vitamin K to work ?

A

2,7,9,10, proteins C and S.

86
Q

What drug is used to inhibit Vitamin K epoxide reductase ?

A

Warfarin

87
Q

Where do we get most of our vitamin K from ?

A

Gut colonies of bacteria

LONG TERMA AB THERAPY DISRUPTS VIT K LEVELS !

88
Q

Describe the Etiology of Heparin Induced Thrombocytopenia (HIT)

A

Heparin binds to factor IV and then attaches to platelet acting as a hapten. The spleen plasma cells make Ab’s agains them leading to destruction of the platelets.
Platelet fragments activate other platelets –> Thrombosis and consumption of remaining platelets

89
Q

What should you never give to a patient with HIT ?

A

Warfarin –> Skin Necrosis

90
Q

Disseminated Intravascular Coagulation (DIC)

A

Pathologic Activation of the coagulation cascade –> widespread micro thrombi , iscehmia and infarction

Consumption of the platelet factors –> bleeding (IV sites, mucosal surfaces)

91
Q

What is the cause of DIC ?

A

Secondary to other disease processes ( Sepsis, Cancer, AML, Rattlesnake bite

92
Q

Labs for DIC
Platetlet Count
PTT/PT
Fibrinogen

A

Decreased
Increased
Decreased (activation of clotting cascade eats up all of the fibrinogen by converting it to fibrin)

93
Q

What products of fibrin degradation are elevated in DIC and can be used to screen the disorder ?

A

D-dimer !!!

94
Q

What is the treatment for DIC ?

A

Treat underlying problem
Transfusion
Cryoprecipitates

95
Q

tissue plasminogen activator (tPA)

A

converts plasminogen to Plasmin

96
Q

Plasmin

A

Cleaves fibrin (and serum fibrinogen), destroys clotting factors and block platelet aggregation–> clot resolution

97
Q

alpha2 Antiplasmin

A

Inactivates Plasmin

98
Q

What is the main reason for Disorders of Fibrinolysis ?

A

Plasmin Overactivity !

99
Q

What molecule released after radical prostatectomy leads to activation of plasmin ?

A

Urokinase (sort of an endogenous tPA)

100
Q

What is the consequence of Liver disease in terms of diseases of fibrinolysis ?

A

alpha2 Antiplasmin is produced in the liver

Liver disease leads to low alpha2 Antiplasmin and thus inability to turn off Plasmin –> increased fibrolysis and inability to clot.

101
Q

Diseases of Fibrinolysis :
PT/PTT
Bleeding time
D-dimers

A

Increased (Plasmin destroys clotting factors)
Increased (fibrin and fibrinogen are destroyed)
Not Present (Lysis products will be increased but D dimers not present since clots don’t form)

102
Q

What is the treatment for Fibrinolytic Disorders ?

A

Aminocaproic Acid (MATT CAPADARCO)

tPA inactivator…(antidote for tPA tox)

103
Q

Although thrombi can form in artery or veins where is the most likely place to see them ?

A

Deep Veins of the leg (DVT)

104
Q

How do you know a thrombus formed before death and not due to post mortem coagulation ?

A

Lines of Zahn
(alternating lines of platelets/fibrin and RBC’s)

Attachment to the vessel wall

105
Q

Virchows Triad (major risk factor for forming thrombus)

A

Disruption of blood flow (Stasis and turbulence)
Endothelial cell damage
Hypercoaguable state

106
Q

What are some examples of situations where normal blood flow is disrupted /

A

Immobilization
Cardiac wall dysfunction (leads to stasis from unordered contraction)
Aneurysm

107
Q

What is the purpose of Prostacyclin (PGI2) and NO ?

A

Vasodialation and inhibition of platelet aggregation.

108
Q

What molecules are secreted by endothelium that inactivate thrombin ?

A

Anti-Thrombin III

109
Q

What molecules are secreted by endothelium that breakdown Fibrin, Fibrinogen and Clotting factors ?

A

tPA

Also inhibits platelet aggregation

110
Q

What is thrombomodulin ?

A

Redirects thrombin to activate Protein C

111
Q

What is the MOA for Protein C ?

A

Inactivates Factors V and VIII (Common and Intrinsic Pathway)

112
Q

What molecule is increased due to b12 deficiency that leads to vascular damage ?

A

Homocysteine

113
Q

What is the role of B12 in Homocysteine management ?

A

Transfers a methyl group to Homocysteine –> methionine

114
Q

How do you know you have a pure B12 deficiency and not a Folate/B12 deficiency ?

A

Measure the level of Methylmalonic Acid

Increased in B12 def not Folate

115
Q

How does Cystathione Beta Synthase deficiency effect homocysteine ?

A

Defect –> high Homocysteine levels and homocysteinuria.

116
Q

CBS def leads to what complications ?

A

vessel thrombosis
Mental retarded
Lens dislocation
Long Fingers

117
Q

Hypercoaguable states are due to excess procoagulant proteins and classically present as :

A

Recurrent DVT
DVT at young age

Legs Head or hepatic (budd chiari ?)

118
Q

How does Protein C or S deficiency lead to hypercoaguable state ?

A

Protein C/S inactivate Factor V and VIII

If they are deficient you will see increased coagulability in the common and intrinsic pathway

119
Q

What otehre complication is associated Protein C/S def ?

A

Warfarin Skin Necrosis

120
Q

Explain how Warfarin Skin necrosis develops in patients with Protein C/S deficiency

A

Warfarin inhibits Vit K Epoxide Reductase
Vit K Eposide Reductase activates Factors 2,7,9,10 , Protein C and S
Initially this will cause a steep decrease in C/S especially if there is a low amount to begin with
This leads to a transient HYPERCOAGUABLE state (C/S are anti-coagulatnt in nature) –> Necrosis of skin

121
Q

What is Factor V Leiden ?

A

Mutated Factor V that cannot be inactivated (by protein C/S)

MOST COMMON CAUSE OF INHERITED HYPERCOAGUABILITY

Dont confuse with Von Willebrands which is the most common inherited Coagulation Disorder.

122
Q

Point mutation in prothrombin gene that increases expression of prothrombin

A

Prothrombin20210A

Prothrmobin –> Thrombin cleaves Fibriongen to fibrin

123
Q

Deficiency in Anti-Thrombin III would reduce the efficacy of which molecules ?

A

Heparin Like Molecules
Heparin

Both activate AT3

124
Q

How can you diagnose an Anti-Thrombin III deficiency ?

A

Give a dose of Heparin
Measure PTT
If PTT does not rise despite heparin induction, you likely have AT3 def.

125
Q

What is the treatment for Anti-Thrombin III def ?

A

HIGH DOSES OF HEPARIN (activates whats left) followed by Warfarin (coumidin)

126
Q

before starting Warfarin, what must you give to be sure that there will not be a transient hypercoaguable state due to unknown Protein C/S deficiency ?

A

Heparin (maintains anticoagulation until Warfarins effect on Protein C/S subside)

127
Q

What drugs taken by women increase the risk of hypercoaguable state ?

A

Oral Contraceptives (containing estrogen)

Estrogen –> increased production of clotting factors

128
Q

Most common kind of embolus

A

Thromboembolus (95%)

Dislodged thrombus

129
Q

Atherosclerotic embolus is due to a plaque that dislodges. How can you tell it is an atherosclerotic embolus ?

A

Cholesterol Clefts are seen in the embolus

130
Q

What conditions are associated with Fat Embolus ?

A 
Bone Fracture (long bones)
Soft Tissue Trauma
131
Q

What are two clinical signs of Fat embolus ?

A

Dyspnea and petechiae on chest after fracture

132
Q

What is the most common causes of gas embolus ?

A

Scuba diving and coming up too quickly

133
Q

Caisson Disease

A

Chronic Gas Embolus characterized by multifocal ischemic necrosis of the bones

134
Q

During medical procedure may gas embolus form ?

A

Laproscopic surgery (gas is pumped in to expand abdomen)

135
Q

What are three symptoms of Amniotic Fluid Embolus?

A

SOB
Neurlogic Symtpoms
DIC (Amniotic fluid is highly thrombogenic)

136
Q

What is characteristic of amniotic embolus on histology ?

A

Swirling pattern of squamous cells from fetal skin.

137
Q

Most common causes of Pulmonary Embolus

A

Thromboembolus (From DVT)

138
Q

Why are most PE’s clinically silent ?

A

The lung has dual blood supply and emboli that reach the lung are usually small

Often self resolving

139
Q

What two conditions must be met in order for Pulmonary Infarction to occur due to PE ?

A

Large or medium artery must be occluded

Pre-existing Cardiopulmonary Compromise

140
Q

Presentation of Pulmonary Infarction

A

SOB
Hemoptysis
Pleuritic Chest Pain
Pleural Effusion

141
Q

What will you see on Ventilation/Perfusion scan in a patient with pulmonary Infarction ?

A

Increased V:Q (Ventilation high, perfusion low)

142
Q

What two imaging studies can be used to detect PE ?

A

Ultrasound

Spiral CT –> Hemorrhagic Wedge Shaped iNfarct

143
Q

Sudden Death due to PE is often attributed to what kind of Lesion ?

A

Saddle Embolus (sits at the bifurcation of right and left pulmonary arteries)

144
Q

Are D-dimers elevated in Pulmonary infarction ?

A

Yes

145
Q

Where do most SYSTEMIC Emboli arise from ?

A

The left heart

146
Q

Where does occlusion of blood flow often occur with systemic embolism ?

A

Lower extremities

Pathoma (15 decks)

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