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Heme / Onc > SM_252b: Coags and Inherited Bleeding > Flashcards

SM_252b: Coags and Inherited Bleeding Flashcards

1
Q

When there is vascular injury, ___

A

When there is vascular injury, thrombogenic components of subendothelial vessel wall become exposed and a hemostatic clot of platelets and fibrin form

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2
Q

Describe physiologic antithrombotic mechanisms

A

Physiologic antithrombotic mechanisms

  • Normal endothelium generates substances that inhibit coagulation: inhibitors of platelet activation
  • Antithrombotic mechanisms: antithrombin III, protein C and S, tissue factor pathway inhibitor, thrombomodulin, fibrinolytic system
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3
Q

Primary hemostasis is ___

A

Primary hemostasis is vasoconstriction and aggregated platelets temporarily plug the injured vessel

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4
Q

Secondary hemostasis is ____

A

Secondary hemostasis is when fibrin formation occurs to form a more permanent clot

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5
Q

Describe coagulation basics

A

Coagulation basics

  • Clotting factors are proteins -> converted to proteases during coagulation -> cleave prothrombin to thrombin -> thrombin cleaves fibrinogen to fibrin -> fibrin monomers polymerize to form the strands of the clot
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6
Q

Coagulation involves stages of ____, ____, and ____

A

Coagulation involves stages of initiation, amplification, and propagation

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7
Q

In initation of coagulation, ____

A

In initation of coagulation, a small amount of thrombin is produced

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8
Q

In amplification of coagulation, ____

A

In amplification of coagulation, thrombin further activates FV, VIII, and XI for a large burst of thrombin generation

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9
Q

Describe natural inhibitors of procoagulants

A

Natural inhibitors of procoagulants

  • Thrombin inhibited by antithrombin and thrombomodulin
  • Factor Va and VIIIa inhibited by activated protein C and its co-factor protein S
  • Factor Xa and TF-factor VIIa is inhibited by tissue factor pathway inhibitor
  • Factor XIa is inhibited by the protease nexin 2
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10
Q

____ is progressive breakdown of a thrombus

A

Fibrinolysis is progressive breakdown of a thrombus

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11
Q

tPA is the initator of fibrinolysis and converts ____ to ____

A

tPA is the initator of fibrinolysis and converts fibrin-bound plasminogen to plasmin

  • Plasmin lyses fibrin to soluble fibrin degradation products
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12
Q

____ are fragments of cross-linked fibrin that are soluble fibrin degradation products

A

D-dimers are fragments of cross-linked fibrin that are soluble fibrin degradation products

  • Reflect amount of fibrin degradation
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13
Q

Describe regulation of hemostasis

A

Regulation of hemostasis

  • Sequential steps activate specific procoagulants -> thrombin generation and fibrin formation
  • Each step is regulated by clotting inhibitors
  • Fibrinolysis results in clot lysis
  • Bleeding or thrombosis can occur when the hemostatic balance between clotting factors and inhibitors is altered
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14
Q

aPTT measures the ___ pathway

A

aPTT measures the intrinsic pathway

  • HMWK, FXII, FXI, FIX, FVIII
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15
Q

PT measures the ____ pathway

A

PT measures the extrinsic pathway

  • FVII
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16
Q

Describe causes of prolonged PT and normal aPTT

A

Prolonged PT and normal aPTT

  • FVII deficiency
  • Early Vitamin K deficiency (FII, FVII, FIX, FX)
  • Liver disease
  • Warfarin therapy (Vitamin K antagonist)
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17
Q

Describe causes of prolonged aPTT and normal PT

A

Prolonged aPTT and normal PT

  • FVIII or IX deficiency
  • Factor XI or XII deficiency
  • Decreases prekallikrein or high molecular weight kininogen
  • Inhibitor (lupus anticoagulant, FVIII inhibitor)
  • Anticoagulant: heparin
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18
Q

Describe causes of prolonged PT and prolonged aPTT

A

Prolonged PT and prolonged aPTT

  • FII, FV, or FX deficiency
  • Hypofibrinogenemia or dysfibrinogenemia
  • Vitamin K deficiency (FII, FVII, FIX, FX)
  • Liver disease
  • Warfarin therapy (Vitamin K antagonist)
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19
Q

Correction to normal on PT or PTT mixing study indicates ____

A

Correction to normal on PT or PTT mixing study indicates factor deficiencies

  • E.g. hemophilia, Vitamin K deficiency, warfarin therapy
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20
Q

No correction to normal on PT or PTT mixing study indicates ____

A

No correction to normal on PT or PTT mixing study indicates factor inhibitor present

  • Acquired specific factor inhibitor or lupus anticoagulant
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21
Q

Even if PT and aPTT are normal, ____ can be present

A

Even if PT and aPTT are normal, mild factor deficiency can be present

  • PT or PTT become abnormal only when coagulation factor levels drop below 30-40%
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22
Q

Describe causes of bleeding

A

Causes of bleeding

  • Vascular / connective tissue: hereditary hemorrhagic telengiectasias, Ehlers-Danlos, scurvy (Vitamin C deficiency)
  • Hematologic: coagulopathy, platelet disorder (thrombocytopenia, platelet function abnormality)
  • Medications: anticoagulants, antiplatelets
23
Q

Describe inherited bleeding disorders

A

Inherited bleeding disorders

  • Vascular: hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu), Ehlers-Danlos syndrome
  • Clotting factor deficiencies: VIII or IX, V / VII / X / XI, XIII, von Willebrand’s disease, hypofibrinogenemia / dysfibrinogenemia
  • Platelet disorders
24
Q

Describe clues to a bleeding disorder

A

Clues to a bleeding disorder

  • Abnormal bruising especially spontaneous
  • Recurrent epistaxis or gum bleeding
  • Prior surgical bleeding
  • Dental extractions complicated by bleeding
  • Menorrhagia
  • History of soft tissue or joint hemorrhage especially with normal activities
  • Iron deficiency or need for transfusions
  • Family history of bleeding disorders
25
Q

Describe clues to bleeding disorders on physical exam

A

Clues to bleeding disorders on physical exam

  • Petechiae: thrombocytopenia
  • Ecchymoses: clotting factor disorder, von Willebrand’s disease, connective tissue disorders, medications, platelet disorders
  • Soft tissue hemorrhage: deficiency of a coagulation factor
  • Telangiectasias (skin, nasal, oral, nails): hereditary hemorrhagic telangiectasias
26
Q

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) is ____ that presents with ____ and ____

A

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) is abnormality in the vascular wall that presents with mucocutaneous telangiectasias and arteriovenous malformations

27
Q

___ is an autosomal dominant disorder that may present with recurrent bleeding from nose or GI tract

A

Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder that may present with recurrent bleeding from nose or GI tract

28
Q

Diagnosis of hereditary hemorrhagic telangiectasia is ___

A

Diagnosis of hereditary hemorrhagic telangiectasia is clinical

  • No specific lab tests
29
Q

Hemophilia A results from a ___ deficiency

A

Hemophilia A results from a Factor VIII deficiency

  • Inversion of intron 22 on factor VIII
30
Q

Hemophilia B results from a ____ deficiency

A

Hemophilia B results from a Factor IX deficiency

31
Q

Hemophilia A or B severity depends on ___

A

Hemophilia A or B severity depends on level of factor activity

  • Severe hemophilia: spontaneous joint hemorrhages (hemarthroses), intramuscular hemorrhage, intracranial hemorrhage, serious bleeding with trauma or injury
  • Moderate and mild: bleeding with surgery or dental procedures, bleeding with trauma or injury
32
Q

Women are ___ of hemophilia A or B

A

Women are carriers of hemophilia A or B

  • Can have clinically significant low factor levels (< 40%)
  • Can have beeding complications
33
Q

Joint bleeds are typically ____ in hemophilia

A

Joint bleeds are typically spontaneous in hemophilia

34
Q

Describe treatment of hemophilia

A

Hemophilia treatment

  • Severe hemophilia: prevention or prompt treatment of bleeding, early treatment and prophylactic therapy for joint bleeds
  • Mild hemophilia: prevention of bleeding with surgery or trauma
35
Q

____ is used to treat bleeding in hemophilia due to mild Factor VIII deficiency

A

Desmopressin is used to treat bleeding in hemophilia due to mild Factor VIII deficiency

36
Q

Antibodies can develop in patients with hemophilia against factor concentrates, leading to ____

A

Antibodies can develop in patients with hemophilia against factor concentrates, leading to resistance to treatment

37
Q

___ are used to treat hemophilia due to Factor VIII or IX deficiency

A

Factor concentrates are used to treat hemophilia due to Factor VIII or IX deficiency

38
Q

VWF functions to ____ and ____

A

VWF functions to bind platelet to the endothelium and increases circulating half-life of Factor VIII because binding protein for Factor VIII

39
Q

Describe vWF

A

vWF

  • Gene on chromosome 12
  • Protein synthesized by endothelial cells and megakaryocytes
  • vWF multimers are stored in Weibel-Palade bodies or alpha granules in platelets
40
Q

Describe lab tests for von Willebrand disease

A

Lab tests for von Willebrand disease

  • Screening testsL bleeding time, PTT
  • Specific tests: von Willebrand antigen, von Willebrand activity, Factor VIII, and Von Willebrand multimer analysis
41
Q

Describe types of von Willebrand disease

A

Types of von Willebrand disease

  • Type 1: partial quantitative deficiency of vWF antigen
  • Type 2: qualitative defect of vWF antigen
  • Type 3: severe quantitative deficiency (similar to severe hemophilia A)
42
Q

Describe Type 1 von Willebrand disease

A

Type 1 von Willebrand disease

  • Most common
  • Decrease in vWF, von Willebrand activity, and FVIII
  • Symptoms: easy bruising, epistaxis, menorrhagia, bleeding with dental extractions or tonsillectomy
  • Not all patients with low vWF levels will bleed
  • Patients with Type O blood have lower vWF levels than patients with other blood types
43
Q

Describe Type 2 von Willebrand disease

A

Type 2 von Willebrand disease

  • Functional defect of protein
  • Type 2A: absence of high molecular weight multimers
  • Type 2B: increasing binding of vWF to platelet glycoprotein 1b resulting in vWF and platelet clearance from circulation
  • Type 2N: abnormal binding of FVIII to vWF -> increased clearance of FVIII
  • Type 2M: impaired binding to collagen or platelet glycoprotein 1b
44
Q
A
45
Q

Describe Type 3 von Willebrand disease

A

Type 3 von Willebrand disease

  • Severe deficiency of von Willebrand protein
  • FVIII levels are very low
  • Can have severe bleeding and similar to severe hemophilia
46
Q

Treatment of von Willebrand disease involves ___ or ___

A

Treatment of von Willebrand disease involves desmopressin or vWF concentrate

47
Q

Hemophilia C is ____

A

Hemophilia C is Factor XI deficiency

  • Autosomal
48
Q

Describe Factor XI

A

Factor XI

  • Activates Factor IX -> results in thrombin generation
  • Thrombin activates Factor XI -> creates positive feedback loop that leads to further thrombin generation
  • Thrombin generation leads to thrombin activatable fibrinolysis inhibitor
  • Factor XI deficiency: less thrombin generation and less TAFI -> increased fibrinolysis
49
Q

Describe bleeding in Factor XI deficiency

A

Factor XI deficiency bleeding

  • Variable hemorrhage
  • Bleeding with surgery or trauma
  • Spontaneous joint or muscle hemorrhage unlikely
  • Mucocutaneous bleeding: ecchymoses, gum bleeding, epistaxis, menorrhagia
  • Delayed post-surgical bleeding
50
Q

Factor XI deficiency is treated with ____ or ____

A

Factor XI deficiency is treated with fresh frozen plasma or antifibrinolytic agents such as e-aminocaproic acid / transexamic acid

51
Q

___ deficiency is the only coagulation factor not reflected in PT or PTT

A

Factor XIII deficiency is the only coagulation factor not reflected in PT or PTT

  • Cross-links fibrin
  • Homozygotes have severe deficiency
  • Treat with FFP, cryoprecipitate, or plasma-derived factor XIII concentration (fibrogammin)
52
Q

Describe clotting factor deficiences NOT associated with bleeding

A

Clotting factor deficiences NOT associated with bleeding

  • Contact activation factors: factor XII, HMWK, prekallikrein
  • Result in elevated PTT but no increased risk of bleeding
53
Q

Describe disorders of fibrinogen

A

Disorders of fibrinogen

  • Congenital afibrinogenemia
  • Hypofibrinogenemia
  • Dysfibrinogenemia

Treat with cryoprecipitate or plasma-derived fibrinogen concentrate (Riastap)

Heme / Onc (41 decks)

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