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Heme / Onc > SM_257b: Thrombophilia > Flashcards

SM_257b: Thrombophilia Flashcards

1
Q

____ is the way blood vessels, blood components, and procoagulants stop bleeding

A

Hemostasis is the way blood vessels, blood components, and procoagulants stop bleeding

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2
Q

____ is physiologic control of bleeding by clot formation

A

Coagulation is physiologic control of bleeding by clot formation

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3
Q

___ is pathological occlusion of blood vessels

A

Thrombosis is pathological occlusion of blood vessels

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4
Q

___ is increased tendency to form thrombi

A

Thrombophilia is increased tendency to form thrombi

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5
Q

____ is bleeding tendency

A

Hemophilia is bleeding tendency

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6
Q

Describe hemostatic balance

A

Hemostatic balance

  • Maintaining blood flow while preserving ability to respond to vessel injury
  • Designed to prevent clots within vessels
  • When vessel injury occurs, coagulation system is activated to prevent or lessen hemorrhage
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7
Q

Procoagulant factors include ____ and ____

A

Procoagulant factors include primary hemostasis and secondary hemostasis

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8
Q

Describe anticoagulant factors

A

Anticoagulant factors

  • Rapid pulsatile blood flow
  • Endothelial surface: non-wettable, NO, prostacyclin, ecto-ADPase, TFPI, thrombomodulin, proteoglycans
  • Natural anticoagulants
  • Fibrinolytic system
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9
Q

Coagulation is ___, ___, and ___

A

Coagulation is rapid, self-limited, and reversible

  • Cells and plasma proteins form a clot in response to vessel injury
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10
Q

Describe phases of clot formation

A

Clot formation

  1. Primary hemostasis: formation of platelet plug at site of endothelial injury, involves endothelium (collagen) / platelets / vWF
  2. Secondary hemostasis: strengthening of clot by coagulation cascade, interaction of platelets / proteins / fibrin
  3. Termination: natural anticoagulants
  4. Breakdown of clot: fibrinolysis
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11
Q

Thrombosis occurs when ___

A

Thrombosis occurs when hemostatic balance is shifted in favor of procoagulants

  • Artery: MI, stroke
  • Vein: PE, DVT
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12
Q

Virchow’s triad consists of ____, ____, and ____

A

Virchow’s triad consists of endothelial injury, alterations in normal blood flow, and hypercoagulability of blood

  • Endothelial injury: physical distribution of endothelium, disruption of balance of pro- and anti-thrombotic effects of endothelium
  • Alterations in normal blood flow: stasis, turbulence
  • Hypercoagulability of blood
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13
Q

Describe arterial thrombosis

A

Arterial thrombosis

  • High flow state
  • Typically more dependent on vascular abnormalities and more rarely a result of coagulation abnormality
  • Platelet rich thrombus (white)
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14
Q

Describe mechanisms of arterial thrombosis

A

Arterial thrombosis mechanisms

  • Injury to vessel wall (most common)
  • Embolism from other source (less common): majority from arteries, rarely “paradoxical” embolism from venous circulation
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15
Q

Describe arterial thrombus on disrupted plaque

A

Arterial thrombus on disrupted plaque

  • Many arterial thrombi form on top of disrupted atherosclerotic plaques
  • Thin fibrous cap and lipid-ruch core prone to disruption
  • Plaque rupture exposes thrombogenic material in lipid core to blood
  • Triggers platelet activation and thrombin generation
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16
Q

Describe examples of arterial thrombi

A

Arterial thrombi

  • Coronary artery: MI, unstable angina (temporary occlusion)
  • Cerebral artery: stroke, TIA (temporary occlusion)
  • Peripheral / lower extremity artery: limb ischemia / gangrene
  • Small vessel peripheral arteries: digital ischemia
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17
Q

Describe venous thrombosis

A

Venous thrombosis

  • Low flow state
  • Occurs with venous stasis: valve cusps, muscular sinuses
  • Red thrombi: contain more RBCs that accumulate on fibrin strands
  • More dependent on coagulation factors than platelets
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18
Q

Describe examples of venous thrombosis

A

Venous thrombosis

  • DVT of legs and arms
  • Pulmonary embolus
  • Portal vein thrombosis
  • Cerebral sinus thrombosis
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19
Q

Compare arterial and venous thrombsis

A

Comparison

  • Arterial thrombosis: rich in platelets (white clot), high shear, antiplatelet drugs are first-line
  • Venous: mostly fibrin and trapped RBCs with fewer platelets (red clot), low shear, anticoagulants are first-line
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20
Q

Describe loss of function inherited thrombophilias

A

Loss of function inherited thrombophilias: loss of anticoagulant activity

  • Protein C deficiency
  • Protein S deficiency
  • Antithrombin deficiency
21
Q

Describe gain of function inherited thrombophilias

A

Gain of function inherited thrombophilias: procoagulant activity

  • Factor V Leiden
  • Prothrombin gene mutation 20210
  • Increased clotting factor VIII
22
Q

Factor V Leiden results from ____

A

Factor V Leiden results from a substitution in base 1691 position 506 resulting in glutamic acid instead of the normal arginine

23
Q

Factor V Leiden mutation renders ___

A

Factor V Leiden mutation renders FVa relatively resistant to cleavage by APC

  • Factor V Leiden does not function as a cofactor for the cleavage of FVIIIa by APC
  • Persistence of activated factors V and VIII increases risk of thrombosis
24
Q

Prevalence of heterozygous Factor V Leiden is ___ than that of homozygous Factor V Leiden

A

Prevalence of heterozygous Factor V Leiden is greater than that of homozygous Factor V Leiden

(overall most commonly found in Caucasians)

25
Q

____ is the most common inherited thrombophilic mutation

A

Factor V Leiden is the most common inherited thrombophilic mutation

  • Risk for venous thrombosis, arterial thrombosis, pregnancy complications
26
Q

Prothrombin G20210A gene mutation results in ___

A

Prothrombin G20210A gene mutation results in gain of function inherited thrombophilia

  • Heterozygous is more common than homozygous
  • Most common in Caucasian population
27
Q

Prothrombin G20210A gene mutation is ___

A

Prothrombin G20210A gene mutation is mutation in the promoter region of gene leading to an increase in prothrombin synthesis

28
Q

Prothrombin G20210A gene mutation leads to ___

A

Prothrombin G20210A gene mutation leads to increased circulating levels of prothrombin (Factor II)

  • Precursor to thrombin
  • Protects factor Xa from antithrombin
  • Higher levels of prothrombin result in greater inhibition of fibrinolysis by activating TAF
29
Q

Elevated factor VII is a ___ inherited thrombophilia

A

Elevated factor VII is a gain of function inherited thrombophilia

  • Found in top decile of population
  • Baseline levels affected by role of FVIII as acute phase reactant
30
Q

Describe quantitative vs qualitative loss of function thrombophilia

A

Quantitative vs qualitative loss of function thrombophilia

  • Quantitative: reduced amounts of protein
  • Qualitative: reduced functional activity, can have normal protein levels but abnormal function
  • Both can cause reduced activity levels
31
Q

Activated protein C ___

A

Activated protein C inactivates factors Va and VIIIa

32
Q

Protein S is a ___

A

Protein S is a co-factor of APC

  • Exists as a free form (1/3) and bound to C4b-binding protein (2/3): free is active form
33
Q

Deficiencies of Protein C and Protein S shift balance toward ___

A

Deficiencies of Protein C and Protein S shift balance toward thrombosis

  • Protein C and Protein S are natural anticoagulants
  • Congenital: quantitative deficiency or qualitative loss
  • Acquired: decreased synthesis, increased consumption, increase in C4BP and resultant decrease in free Protein S
34
Q

Homozygous Protein C or S deficiency leads to ___

A

Homozygous Protein C or S deficiency leads to purpura fulminans

  • Rare, life-threatening
  • Characterized by extensive tissue thrombosis and hemorrhagic skin necrosis
35
Q

Heterozygous Protein C or S deficiency leads to ___

A

Heterozygous Protein C or S deficiency leads to increased risk of first thrombosis

36
Q

Protein C or Protein S deficiency confers risk for ____ upon initiation of warfarin

A

Protein C or Protein S deficiency confers risk for warfarin-induced skin necrosis upon initiation of warfarin

  • Levels of protein C drop faster than other clotting factors inducing a transient hypercoagulable state
37
Q

Homozygous antithrombin deficiency is ___

A

Homozygous antithrombin deficiency is fatal in utero

38
Q

Antithrombin ____

A

Antithrombin binds to pentasaccharide sequence on heparin and proteoglycans, forming trimolecular complex that inactivates thrombin

39
Q

Congenital mutations leading to antithrombin deficiency can be in ___

A

Congenital mutations leading to antithrombin deficiency can be in regions that inactivate thrombin or cause defects in heparin binding to decrease antithrombin deficiency

  • Lose natural anticoagulant activity
40
Q

Describe when acquired antithrombin deficiency occurs

A

Acquired antithrombin deficiency

  • Prematurity
  • Liver disease
  • Nephrosis
  • Malnutrition
  • IBD
  • L-asparaginase
  • Estrogen therapy
41
Q

Antithrombin deficiency leads to ___

A

Antithrombin deficiency leads to relative heparin resistance

42
Q

Antiphospholipid antibody syndrome is ___

A

Antiphospholipid antibody syndrome is acquired

  • can be primary or secondary
  • Associated with arterial and venous thrombosis and pregnancy complications
43
Q

Antiphospholipid antibody syndrome involves autoantibodies directed against ___ and ___

A

Antiphospholipid antibody syndrome involves autoantibodies directed against phospholipids and phospholipid binding proteins

  • Lupus anticoagulant, anti-beta-2 glycoprotein antibody, and anti-cardiolipin antibody
  • Precise pathogenesis resulting in clinical complications is unknown
44
Q

Diagnosis of antiphospholipid antibody syndrome requires ____ and ____

A

Diagnosis of antiphospholipid antibody syndrome requires lab and clinical criteria

  • Positive on 2 occasions separated by at least 12 weeks
45
Q

Describe lupus anticoagulant testing process

A

Lupus anticoagulant testing

  1. Prolongation of clot based assay
  2. Does not correct with mixing study
  3. Phospholipid dependence
  4. Lupus anticoagulant positive
46
Q

Lupus anticoagulant testing can be falsely positive in setting of ____

A

Lupus anticoagulant testing can be falsely positive in setting of anticoagulation

(UFH, warfarin, DOAC)

47
Q

Polymorphisms in MTHFR gene may but do not necessarily ____ so ____ screen

A

Polymorphisms in MTHFR gene may but do not necessarily increase levels of homocysteine so do NOT screen

  • Thermolabile variant present in 37% of Caucasians does not increase risk of venous thrombosis or pregnancy complications
48
Q

Describe when to test for inherited thrombophilias

A

When to test for inherited thrombophilias

  • Only if information obtained will influence management and outweigh potential risks of testing
  • Timing of testing: proteins consumed during acute event, take weeks to return to baseline
  • Testing can also be affected by anticoagulants
49
Q

____ test for inherited thrombophilia if thrombosis occurs in the setting of a major transient risk factor

A

Do NOT test for inherited thrombophilia if thrombosis occurs in the setting of a major transient risk factor

Heme / Onc (41 decks)

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