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Flashcards in Defects of Coagulation mechanism Deck (55):
1

What are the 3 main types of bleeding disorders?

acquired platelet defects
inherited bleeding disorders
acquired coagulopathy

2

What is hemostasis?

process that prevents blood loss form damaged blood vessels

3

What is thrombosis?

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

4

What important factor is needed for platelet adhesion? Receptor?

vWF
GPIbalpha

5

What important factor is needed for platelet aggregation? Receptor?

Fibrinogen
GPIIb/IIIa

6

What is contained in dense granules in the platelet?

ADP, ATP
seratonin
calcium

7

What does calcium release lead to?

integrin activation
granule secretion

8

What are the 2 binding domains on vWF?

Gp1b
GPIIb/IIIa

9

What does binding of vWF with GP1b cause?

braking/activation of the platelet

10

What does binding of vWF ith GPIIb/IIIa cause?

arrest of the platelet

11

What does platelet granule release lead to?

signals other platelets

12

What does platelet membrane coagulant expression lead do?

thrombin and clot

13

Initiation phase of cell based coagulation

activaion of IXa & Xa
Xa converts II to IIa (thrombin)

14

Amplification phase of cell based coagulation

thrombin activated Va, VIIIa, XIa and platelets

15

Propagation of cell based coagulation

IXa catalyzing further thrombin formation
XIa augments by driving further IXa formation

16

Thrombin driven pahse of cell based coagulation

transformation of fibrinogen to fibrin and cross linking

17

What are the vitamin K dependent pro coagulant factors?

II, VII, IX, X

18

What are the vitamin K dependent anti coagulant factors?

Proteins C & S

19

What does thrombin activate?

Fibrinogen to fibrin
Factor XIIIz
TAF1

20

What does an intrinsic pathway deficiency lead to?

increased PTT

21

What does an extrinsic pathway deficiency lead to?

increased PT

22

What enzymes are important for the fibrinolytic system?

t-PA
Plasminogen
alpha-antiplasmin
D-dimer

23

What does active protein C do?

proteolysis of factors Va and VIIa

24

What does mucosal bleeding usually indicate?

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