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I3 Exam 1 > Laboratory Studies of Hemostasis - Wong > Flashcards

Laboratory Studies of Hemostasis - Wong Flashcards

1
Q

What is INR used for

A

concentration of warfarin - anticoagulant therapy

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2
Q

What would an anti-Xa test be used for?

A

heparin concentration

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3
Q

sodium citrate tube

A

blue top tube

- anticoagulant

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4
Q

What are causes of prolonged bleeding time

A

thrombocytopenia
VWD
platelet dysfunction
vascular dysfunction

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5
Q

Prothrombin time

A
  • platelet poor plasma obtained from blood sample
  • citrate
  • tissue factor, phospholipid, calcium as reagents
  • time to clot detection
  • sensitive to factor VII
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6
Q

How does warfarin affect PT?

A

elevated PT

- affects factor VII

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7
Q

What does heparin do?

A

binds AT III which binds anti-coag factors in intrinsic and extrinsic

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8
Q

How does heparin affect PT?

A

elevated PT

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9
Q

What are the common pathway factors?

A

I (fibrinogen), II, V, X

1x2x5=10

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10
Q

What happens if you don’t have enough fibrinogen

A

prolonged PT

- fibrin isn’t adequately getting properly formed

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11
Q

What do inhibitors lead to?

A

elevated PT

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12
Q

How do you calculate INR

A

PT/PT(normal) raised to the ISI (international sensitivity index)

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13
Q

What is added to the tube when checking for aPTT

A
  • add an activator - silica, kaolin
  • phospholipid
  • calcium
  • tissue factor is not used
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14
Q

What can elevated FVIII cause to the aPTT

A

shortened

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15
Q

What does a FVIII inhibitor do to PTT

A

elevated aPTT

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16
Q

How is thrombin time measured?

A

thrombin and calcium are added to the plasma

  • measure clot formation
  • conversion of fibrinogen to fibrin
17
Q

What can cause an elevated thrombin time

A

heparin

18
Q

How would dysfibrinogenemia/hypofibrinogemia affect thrombin time

A

elevated thrombin time

19
Q

How can you confirm that a prolonged TT is due to heparin?

A

test using reptilase will be normal

20
Q

What will the TT and the reptilase be in dysfibrinogemia?

A

TT and reptilase are prolonged and immunologic assay for fibrinogen will be normal

21
Q

What are autoantibodies specific to?

A

lupus-like type or secondary to an underlying autoimmune disorder

22
Q

What are alloantibodies

A

anti-factor VIII in a patient with hemophilia A following factor VIII concentrate infusion

23
Q

what is the autoantibody specificity of lupus-like coagulant?

A

plasma beta2-glycoprotein I which binds to coagulation factors

24
Q

What is PF4?

A

neutralizes heparin in heparin level determination

- when samples aren’t properly spun down

25
Q

How quickly should assays be run?

A

less than 2 hours because factor V and VIII are labile

26
Q

what is the steps of the mixing study

A

first exclude heparin

  • immediate and incubate mixture of patient and normal plasma
  • see if it corrects
27
Q

What would lupus anticoagulant cause in the mixing study

A

won’t correct

- nonspecific inhibitor

28
Q

Patient with PT of 22 sec, PTT of 67

  • normal fibrinogen
  • no recent history of coumadin or heparin
  • mixing study: PT: 13 sec, PTT: 32 sec
A

factory deficiency because correction of PT and PTT

29
Q

How do you test for lupus-like anticoagulant

A

factory specific inhibitor

30
Q

Which 3 factors are not associated with bleeding?

A

factor XII, prekallikrein, kininogen are not associated with bleeding

31
Q

What does the factor V leiden mutation cause?

A

resistance to protein C

- increase inability to clot

32
Q

protein S/C deficiency

A

less ability to activate factor V = more clotting

33
Q

ATIII

A

major inhibitory protein for clotting cascade

34
Q

lupus anticoagulant

A

LA = immunoglobulin which interfere with steps of clotting resulting in prolonged coagulation

35
Q

What causes the antiphospholipid antibody syndrome?

A

increase in cardiolipin and beta2-glycoprotein I antibodies

36
Q

What does APS criteria require

A

1 clinical and 1 laboratory finding

I3 Exam 1 (12 decks)

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