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Heme/Lymph > Defects of Coagulation mechanism > Flashcards

Defects of Coagulation mechanism Flashcards

1
Q

What are the 3 main types of bleeding disorders?

A

acquired platelet defects
inherited bleeding disorders
acquired coagulopathy

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2
Q

What is hemostasis?

A

process that prevents blood loss form damaged blood vessels

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3
Q

What is thrombosis?

A

pathological formation of a ‘hemostatic’ plug within the vascularture in the absence of bleeding
(excesive hemostasis)

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4
Q

What important factor is needed for platelet adhesion? Receptor?

A

vWF

GPIbalpha

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5
Q

What important factor is needed for platelet aggregation? Receptor?

A

Fibrinogen

GPIIb/IIIa

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6
Q

What is contained in dense granules in the platelet?

A

ADP, ATP
seratonin
calcium

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7
Q

What does calcium release lead to?

A

integrin activation

granule secretion

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8
Q

What are the 2 binding domains on vWF?

A

Gp1b

GPIIb/IIIa

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9
Q

What does binding of vWF with GP1b cause?

A

braking/activation of the platelet

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10
Q

What does binding of vWF ith GPIIb/IIIa cause?

A

arrest of the platelet

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11
Q

What does platelet granule release lead to?

A

signals other platelets

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12
Q

What does platelet membrane coagulant expression lead do?

A

thrombin and clot

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13
Q

Initiation phase of cell based coagulation

A

activaion of IXa & Xa

Xa converts II to IIa (thrombin)

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14
Q

Amplification phase of cell based coagulation

A

thrombin activated Va, VIIIa, XIa and platelets

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15
Q

Propagation of cell based coagulation

A

IXa catalyzing further thrombin formation

XIa augments by driving further IXa formation

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16
Q

Thrombin driven pahse of cell based coagulation

A

transformation of fibrinogen to fibrin and cross linking

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17
Q

What are the vitamin K dependent pro coagulant factors?

A

II, VII, IX, X

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18
Q

What are the vitamin K dependent anti coagulant factors?

A

Proteins C & S

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19
Q

What does thrombin activate?

A

Fibrinogen to fibrin
Factor XIIIz
TAF1

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20
Q

What does an intrinsic pathway deficiency lead to?

A

increased PTT

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21
Q

What does an extrinsic pathway deficiency lead to?

A

increased PT

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22
Q

What enzymes are important for the fibrinolytic system?

A

t-PA
Plasminogen
alpha-antiplasmin
D-dimer

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23
Q

What does active protein C do?

A

proteolysis of factors Va and VIIa

24
Q

What does mucosal bleeding usually indicate?

A

platelet defect of vWF

25
What does deep tissue bleeding usually indicate?
factor deficiency
26
Generalized oozing at venipuncture sites is indicative of?
DIC
27
What are screening tests done for platelet phase problems?
platelet count | PFA-100
28
What are screening tests done for coagulation phase problems?
PT PTT Fibrinogen Inhibitor screening (1:1 mix)
29
How do we check for quantitative defects of platelets?
peripheral blood film | Vit B12, PF4 ELISA
30
What causes decreased platelet production?
vit B12 deficiency | marrow failure or disease
31
What are peripheral destruction syndromes that can cause thrombocytopenia?
``` DIC (non-immune) Immune -Fab mediated (ITP) -Non-Fab mediated (heparin induced, TTP) -innate immunity (sepsis) ```
32
ITP types and features
childhood-abrupt, viral syndrome, autoantibody to platelet surface glycoproteins, most patients recover adult-insidious, only 5% spontaneous recovery both have large platelets
33
HIT (heparin induced thrombocytopenia) features
immune disease, neo epitope (heparin:PF4) causes transient autoimmune disease (4-14 days into heparin tx) moderate thrombocytopenia associated with thrombotic events confirm w/PF4-Heparin elisa stop heparin, begin alternate anticoag tx
34
Thrombotic microangiopathies
microangiopathic blood films - TTP - HUS - DIC - Sepsis
35
TTP features
``` microangiopathic hemolytic anemia thrombocytopenia renal failure mental status change fever ADAMTS13 ```
36
What is the role of ADAMTS13?
regulates vWF/platelet interaction (cleaves vWF)
37
How do you treat TTP?
plasma exchange
38
What does PFA-100 screen for? measure?
screens for platelet and vWF function measures occlusion time sensitivity/specificity lower than desireable
39
What are the functions of vWF?
supports platelet adhesion carrier for factor VIII abnormalities lead to long PTT
40
Screening for vWF disease?
PFA-100 PTT assay vWF
41
What is bernard soulier syndrome?
congenital absence of GPIb | platelet function defect
42
What is Glanzman's thrombasthenia?
congenital absences of GPIIb/IIIa | platelet function defects
43
How is a PT test performed?
Tissue factor, phospholipid and Ca2+ are added to citrated plasma and clotting time is measured
44
What is INR?
normalized PT so that result is comparable across labs intended for warfarin monitoring (pts PT/mean normal PT)^ISI
45
What is the 1:1 mix test?
pt plasma is mixed with normal plasma with all factors, clotting time is performed on mixed sample if clotting time corrects to normal: factor def likely if clotting time remains prolonged: "inhibitor" likely
46
DDX of isolated long PTT?
``` Factor deficiency inhibitors present (heparin, lupus anticoag, specific factor inhibitor) ```
47
DDX of isolated long PT?
Factor deficiency -VII _vit K defic, oral anticoag, liver disease
48
What factors are not tested by screens?
Factor XIII | Anticoagulants (Proteins C&S, factor V leiden)
49
Prolonged PT and PTT DDX?
``` factor deficiency (isolated or combo [liver disease, vit K defic, DIC]) inhibitors present (isolated factor inhibitor, drugs, lupus inhibitor) ```
50
What factor is deficient in Hemophilia A?
VIII
51
What factor is deficient in Hemophilia B (christmas disease)?
IX
52
How is hemophilia inherited?
X linked
53
Sx of hemophilia?
hemarthrosis & deep muscle bleeds prolonged PTT (corrects on 1:1 mix) sx correleate with level
54
Problems causing vitamin K deficiency?
drugs-oral anticoags (warfarin), antibiotics that decreased bowel flora (less vit K synthesis) malabsorption or dietary deficiency liver disease newborns
55
What occurs with liver disease in regard to anticoagulation?
``` deficiency of multiple coag factors -pro: II, VII, IX, X & V -anti:antithrombin, protein C, protein S thrombocytopenia -hypersplenism -decreased TPO production ```

Heme/Lymph (18 decks)

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